Supermarket Sleuths: Why the 'one-stop shop' is still winning the supermarket war, despite Aldi's low prices

OPINION -- I've been shopping at Aldi for almost two decades, and credit it with being able to feed my family during times of struggle.

Thankfully our times of struggle are over, but the discount grocery retailer remains my go-to when it comes to groceries, except for one thing.

One of Aldi's 'quirks' is that while the majority of its range is consistent, many other items are for a "limited time only" – and sometimes, items in the core range are switched to being part of the "limited time only" range.

A recent example of this is the Colway Spicy Barbeque Sauce, which was once part of the core range but has now moved to "limited time only", leaving some shoppers desperate to stock up on it while they can.

There are also the frequent times Aldi shelves haven't been restocked, for whatever reason, meaning we can't find everything on our shopping lists in a single visit.

For shoppers like me who pretty much buy the same groceries every single week, not being able to find one of our favourite items is really annoying.

And this is why I have never been able to exclusively shop at Aldi for all of my family's grocery needs.

READ MORE: Coles shoppers relief as supermarket saves chicken deal

READ MORE: I finally tried the legendary Costco sheet cake

READ MORE: Why Aussie shoppers need to stock up on their favourite produce

I've always had to pop into a Coles or a Woolworths to grab other items Aldi has never sold, has stopped selling, or sells only occasionally as part of the "limited time only" range.

I know the major supermarkets will have every item I need in stock. I don't know this for sure about Aldi.

The store seemingly embraces this, with one of its advertising campaigns reading "Shop Aldi First", acknowledging shoppers will likely visit another grocery retailer after their trip to Aldi.

Consumer expert Janneke Blijlevens from RMIT says Aldi's loyalty is built on its reputation as being "always being budget-friendly, and good quality" rather than on a loyalty points system like Coles' FlyBuys or Woolworth's Everyday Rewards.

"Indeed, at Aldi you know exactly what you are going to get, for which price, and that the quality is consistent with that price," she told nine.com.au.

"You can budget for the week and buy what you need without feeling like you run in too many surprises."

Blijlevens explained this facilitates "habitual shopping and as a result makes meal planning and household budgeting, and eventually household routines more efficient and less effortful".

And that is key. I've always argued finding the lowest prices possible isn't the only consideration for busy, budget-savvy families.

They also need the time to find them, and sometimes they have to pay prices that aren't necessarily the lowest, but that are low enough because of convenience.

This alleviates a "mental load".

Now, imagine you are one of those customers who is loyal to Aldi "precisely because of the consistent and low effort experience while shopping".

"Then when a product suddenly becomes unavailable, it takes conscious effort to replace this item with something equivalent, it breaks your routine and the efficiency that you are used to," Blijlevens said.

And families whose budgets are tight enjoy at their little treats, such as Colway Spicy Barbeque Sauce.

Other items I have noticed coming and going from Aldi over the past few months include Food Envy Vanilla Protein Custard Pouch and International Cuisine Frozen Butter Chicken, which eventually returned.

Choceur Coconut Crunch chocolate, which may not have sold as many as Aldi would have liked, may have been the weekly treat of a time-poor budget-conscious mum or dad. Same with the Very Berry Muesli and the Dairyfine Blonde chocolate bars.

"It is not just that product, it is a whole system and routine that an Aldi shopper is accustomed to," Blijlevens said.

"Suddenly, Aldi is not delivering on your expectations for a consistent shopping experience that has become your routine and habit ingrained in your household management system.

"When our routines and habits are interrupted, our brains experience this as highly negative, because it disrupts the neural pathways that have been developed.

"Suddenly it needs to spend extra effort and time to make a decision and rewire those neural pathways that were so well established.

"We make thousands of different decisions and choices each day. We rely on habits so our brains are able to deal with all those choices and decisions it has to make in a day.

"This effect of discontinued products is more pronounced for loyal Aldi shoppers precisely because Aldi has set an expectation of shopping being efficient, and consistent, and Aldi shoppers have tied an entire household management system to that expectation consistency in their offering of products."

This, in my mind, is why Aldi will never be as big as Coles and Woolworths, and perhaps they never intended to be.

Coles and Woolworths' current market share, according to the ACCC, is approximately 67 per cent combined, next to Aldi at around 10 percent.

Although Aldi's market share is growing, and tends to spike during times of financial stress, such as after interest rate increases.

It is possible to shop exclusively at Aldi, and make do with what they sell. I did so, for many years.

But I have also found that during times of financial struggle, saving on grocery items is important, but so is reducing the mental load.

This may explain why, despite its reputation has having lower prices, Aldi still falls far behind Coles and Woolworths when it comes to grocery sales in Australia.

FOLLOW US ON WHATSAPP HERE: Stay across all the latest in celebrity, lifestyle and opinion via our WhatsApp channel. No comments, no algorithm and nobody can see your private details.