They are not even remotely the same. "should of" is a phonetic issue. of is spoken with the schwa vowel uh, so the o sounds like uh, and the f takes the v sound, so "should of" sounds like "should uhv", and "should have/should 've" sounds exactly the same, "should uhv". The issue is that folks that don't read much hear "should uhv" and think it's should of, so when they write "should of" because they expect should 've to sound like "should have" even tho they completely use the contraction when they speak!

It's like saying that people with accents come across as uneducated when it come just be that the person has a deafness to American th and hears t does a substitute so they will say ting instead of thing or tin in place of thin. With that said, I grew up speaking/hearing the form of British english and "Try and" sounds perfectly fine to me.