Because their population is MUCH smaller and they already use much less gasoline, so the scope of the problem is much smaller. In addition, they make ethanol out of sugar (cane, I think) which is a MUCH MUCH more efficient way to make ethanol. My understanding is that making sugar from corn, like we do in the US, uses a lot of energy and so the net energy you get out of it isn’t very much.
Also, imagine a significant portion of the US went to corn-produced ethanol. Imagine how much fertilizer we’d be dumping into our rivers and seas. It’s quite bad already, I’m not sure I’d want to increase the problem by 100, or 1000, or 10,000 times.
There are newer forms of ethanol production that are being worked on (cellulosic ethanol?) that is a process that can work with a lot of organic waste materials: sawdust, sticks, I dunno, lots of stuff. Politicians like to talk about this one a lot, so that makes me suspicious that it’s just something in the future we can point to so that we don’t have to do anything NOW.