It's all just branding, though: big companies spend a fortune to convince you that they are obviously the best, so you'd be a fool to consider if there are any other options.
Sometimes branding does equal better quality; usually they're no better (or can even be worse) than like-for-like supermarket own brands at a third the price; sometimes it isn't even any more convenient, quicker or better than just doing it yourself.
Like with the frozen jacket potatoes, oven chips are obviously quicker and more convenient; but the very best of them are a very pale imitation of proper home-made chips.
You still get all the adverts from McCain suggesting that it's accepted they are the best chips, when they aren't even the best oven chips you can buy - by a very long chalk. I suppose they wouldn't sell nearly as many if they said "Proper home-made chips are 20 times nicer; but if you don't have the time, equipment, any potatoes in or just can't be arsed with that, ours are a middling alternative".
Nevertheless, they've been successful in their branding and advertising to the point where I'll bet the majority of people under 30 wouldn't even realise that you can make your own chips from scratch as an option.
The weirdest one to me is the bags of ice cubes that supermarkets sell. I totally get if you're having a party and you need a load of them and/or you need them NOW; but I know people who will buy a bag of ice cubes from the supermarket just for their everyday freezer stock, using them gradually a few at a time.