Why is it so hard for people to use capitalization and punctuation!?

Not to mention proper spelling and grammar. There is no excuse when you’re typing something on a computer. It’s so easy to find the right way to spell something, etc.

Is it because people are lazy or just stupid? I find it hard to belive that an adult doesn’t know the difference between “two” and “too”, or why someone would put a period directly after a question mark? I could go on and on. This is driving me mad.