A lot of people simply don't care because "I don't have a choice, I have things to do" or they think that for some reason warnings/limitations do not apply to them, or some combination. To them, the warning that they will have to slow down and will have limited safe travel range is unfair, therefore the warning is to be ignored because it's getting in the way of the things they have to do.
This attitude comes up often with customers who aren't very car savvy. If they don't like what is needed to actually fix the car, they decide it's unfair, they are getting ripped off, and they won't do it.
In some ways, this is a good reason for the inflator kits that many cars now come with instead of a donut. A full size tire/wheel filled with slime is probably safer than a worn down donut tearing along at 75 MPH. Worse for the shop that has to deal with it later, but less risky for the public maybe than donuts. Of course, when the people who drive for months on a donut find out their car doesn't have one, they pitch an unholy fit about it, because now the manufacturer is ripping them off, they got cheated out of the free tire that comes in the trunk, they don't want to pay $250 or whatever for a kit, because they were supposed to get a free tire in the trunk, etc. And of course they will NEVER buy X brand again because they are so mad about getting cheated out of the tire they were going to drive on for months or years.
