For most people, taxes are not as complicated as they are made out to be. If you can file a 1040EZ you can fill out the form in 10 minutes. If you have a "normal" return with mortgage interest it's still not that difficult.
Most people are just afraid of making mistakes (it's not a big deal if you do, you'll get a notice and you file an amended return). Or maybe they just feel their time is too valuable to spend an afternoon filling out forms. But most individual tax returns are really not that complicated.
Making sense out of the ambiguously-worded instructions has always been the complicated part for me. I have always found this to be infuriatingly stressful, so I hire professionals to deal with it.
The trick is to not try to infer anything that is not there. The instructions are dumbed down to the point they actually are hard to understand. Just do literally what they say and don't think about whether it makes any sense.
Most people are just afraid of making mistakes (it's not a big deal if you do, you'll get a notice and you file an amended return). Or maybe they just feel their time is too valuable to spend an afternoon filling out forms. But most individual tax returns are really not that complicated.