I don't get this. Recently, people have been trying more and more to not use the incorrect "should of", but instead of using the proper contraction (in the title), they often use "should have". That just makes it look weird and too formal.
It reminds of year 11 where my english teacher had to go out of her way to teach most of the class to not use 'could of' and 'should of' and use 'could've' and 'should've' instead
They're still shook it's not "should of", they don't want to disturb the balance…
I guess this is the result of Internet grammer Nazis. A lot of people are too worried over sounding correct rather than letting language evolve like it should.