It's not laziness! Nobody makes a conscious effort to spell words properly. Nobody sits at their keyboard and figures "Gee, it's easier to spell it hampster than hamster, so I'll do it that way". When writing or typing, spelling common words is an innate sense, something that comes naturally without thought. When you learn to read, words are imprinted on your brain. You might know "i before e except after c..." as a rule to help you with unfamiliar words, but you either know how to spell "believe" or you don't.
Bad spelling of common words in your primary language is a sign of low intelligence. It's a clear indicator that the writer does not know the difference between "your" and "you're", "there" "their" and "they're", "way and weigh". Failure to correct common typos is laziness. Using a sentence like "Over their, those people can't find they're keys, there looking in the wrong place" is just stupidity.