Sure spectators can get in the way some times but it's not that bad really. Try working on a pro race team where there is an open paddock policy. It is hard to walk around let alone get the car to the pits.
Most of the time the spectators just don't know they are intruding at times and all it takes is a little polite conversation to remind them when they might want to stand clear.
Also take for example the save the salt movement. That went national with petitions signed by thousands of spectators. Many of them have never even been to Bonneville and only signed their support because they know it as a special place to many people and a legendary motorsports venue.
