Australia

And for most products for most people, that's fine. But for some products, many people will have a genuine preference for the name brand. And it only takes one or two of those before the inconvenience of going to two different shops will lead people to going to Colesworth instead. The same reason people tend not to go to separate grocers, delis, and butchers.

For example, these days my usual breakfast is Vita Brits. I prefer them over Weet-Bix because they are lower in sugar. A quick look at Choice backs me up on this, with neither Weet-Bix nor the Aldi alternative appearing in their low sugar or low salt best-of list. (Though apparently I could switch to the Woolworths homebrand product.)

A while ago, my go-to was Cornflakes. Health was less of a concern there than texture and taste. And I did try the Aldi product once, and it was frankly terrible.

For other people it might be a children's snack/lolly. Or a particular washing powder/liquid/tablet. Or a particular variety of a particular fruit. But people are time poor, and a lot of people won't go to two places if they can get everything they need from one place.