FlyJSH

First, RC airplane and helicopter pilots are controlling the plane bylooking at it rather than a monitor downlinked from an onboard camera. At a distance of 400 feet, it starts to get hard to tell the heading or attitude of "average" sized planes, so keeping the craft close is pretty important.

There is a long history of keeping models away from airports because, back in the '60s and on, the better radios operated between 72 and 75 mhz. With Marker Beacons transmitting on 75 mhz and the wider bands the RCs were using, it was quite possible to have a meaconing event.

Since a decent sized field is required to keep an RC plane out of the trees, most folks fly outside of town and usually at an RC club. All clubs I ever heard of required membership in the Academy of Model Aeronautics. Some even required a written and/or flight check before becoming a full member.