As you say you get what you pay for but some budget tyres are better than others. If you drive a R75 and waft around without putting any stress on them then fine but the only down side is if you were doing 70 mph on a motorway in heavy rain the budgets will not stop you as quickly as premium tyres in an emergency. Might not seem much but that 10 Meters might be the difference between you slamming into the back of a lorry or not.
Budgets (money wise) are different for everyone so it would be wrong to judge why people have a particular brand.
I have Conti 3s on my car as thats what was fitted from new. They are a great all rounder esp in the wet but the down side is they are a soft tyre so wear out quickly and I have noticed when you get near the wear bars the performance does drop considerably. Ive got a full set of Conti 5s to go on when these are on the wear bars. Not cheap but I just save up for them over a period of time.(They are £100 a corner!
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