no need to put the word "professional" in front of it...the term "professional" is a loose term...basically "professional" means you get paid to do a certain job...i used to be & still know plenty of very good photographers who do it as their passion & dont get paid...but if you looked at their photos, you would consider them "professional"
most if not all racing organizations, tracks, etc require the photographer to be on assignment for an approved media outlet...
being in other people's way? not really...the only time i even came remotely close to blocking someone's view or impeding them from a cell phone picture was during the driver parade announcement before the Sunday race...I was there working, I was there to do a job...I try not to be rude & completely block someone, but there are times where I may step in front of someone to get a shot, but i dont ever camp there & intentionally block their view...i had a lady very rudely tell me "wtf?! why are you in MY way?! move please!!!" i turned around, looked at her, turned back around & continued to do my job...had she been polite & asked me nicely, i would have gladly crouched down, moved a step over, or went to an entirely different area...but since she didnt, i stayed where i was & continued to get the shots i needed/wanted