Flying control line inside a building (or sandwiched between very close buildings) almost demands electric power, just based on noise. It is very disconcerting to fly with echos bouncing off walls and coming at you from multiple directions. They aren't even all in phase, so it's worse than you might think. Best solution was earplugs--and then a set of earmuffs over the top of that....
As far as the whole regulation issue, I would agree that the noise pushed our welcome out of local parks and schools. And, the liability. Before we blame "the guvment" too much, look at who was doing all the suing. It wasn't the guvment, it was people who didn't want to be bothered with other peoples' nuisances. I think this had a lot to do with population density; at least it seemed to in California. As the cities got bigger, there were more people doing those activities, and instead of an occasional nuisance, it became all the time. I'm sure there are other factors, but that is one.
As far as the newest regulations which redefine (or attempt to) everything as a "drone," getting the processes hammered out was painful--and it still isn't done. But as Mark said, it can be done. Our field is within the 5 mile radius and was likely one of the first shut down by the FAA while the whole LOA process was alpha-tested. The AMA/FAA announced a slight improvement in the altitude restrictions very recently where they took some of the discretization out of their grid system, which might help some. And, at least at our field, we have evolved to the understanding with the local FAA guys that "control line don't count." A healthy place to be....
But I tell you what: when Doc hits his number and becomes a billionaire this year, I'll help design the indoor control line stadium with a recirculating wind tunnel to feed one wall and suck it all up on the opposite side. It should come with a knob on the pit controller so you can pick a windspeed that is good for your plane, engine power level and state of trim. I figure we can also put in an overly intense light fixture we can move into place for the ProStunt guys who would rather fly outside and use their "look into the sun" skills which help differentiate them from a Joe Bellcrank, or three. Might even consider some auto-scoring features to help the judges out like verifying the extent of the takeoff role. And, I would like a "shade tree" installed inside by the pit area because, well, we're used to all crowding into the shade and doing most of our armchair flying from there. As long as that fits in Doc's building budget, that is.
The Divot