You lose this ability to check timings with a non-fixed timings, and have to rely on 'oh, it's probably about half an hour from here to here' or google's guess at the real timetabled journey you'll do (which the operator hasn't really promised you at any stage.) People don't seem to mind this too much.
I wonder if part of this is that waiting for a bus is usually less pleasant than being on one in countries where there is often cold/windy/rainy weather. That's something you don't really get with long-distance trains or planes. I'm going to be grumpy if I have to wait in the pouring rain for 15 minutes, even if I still make it to my appointment on time.