It's more free of consequences in a very low margin business though - if they drive a couple of customers away with the ads, they were only making a few pennies

It's more free of consequences in a very low margin business though - if they drive a couple of customers away with the ads, they were only making a few pennies from them anyway. In a higher margin business, the cost of losing customers is higher so the ad revenue would have to be very high to offset that, so you're less likely to see intrusive advertising.