Happy to have my flawed thinking corrected - can you share the examples?

I likely am thinking of a narrow set of "regular businesses" - what came to mind were corner shops, hairdresses, bars or restaurants etc. Even in those cases there are obviously large successful busniesses that do have competitive advantages - but I suspect they mostly get erroded away by competition rather than the business being able to sustain them, and high margins. I would love some counter examples though!

As an example, I would say Microsoft is a regular business. Sure, at this point they're one of the largest companies in the world, but the way they operate is still largely the same as it has been. It ticks all the boxes you described as well.