I'd love to hear from a non-United fan - as I'm biased as can be - but it really does feel we get 'made an example of' more than other clubs with refereeing decisions. Rooney's swearing, outrageously soft ones like Casemiro, Martial - the stupid penalty against Lindelof which then saw the rule change the next week etc.
Not lots of little decisions in a given match, but the 'you know that's the only time that's happened' types. Off the top of my head:
Rooney banned for swearing at a camera
Rooney and Scholes banned from a pre-season red
Neville sent off for flicking a ball into the crowd (I remain convinced he was trying to hit the ad hoardings)
Martial sent off for maybe, a tiny bit touching a face, after himself being throat grabbed
Lindelof's handball which then saw the rule change
Casemiro's 'intervention' from VAR
My point of all of the above is that there are countless examples of other players doing all of these, but the punishment was only for United. As far as I know, the same rules and rigour just simply aren't applied to them.