As someone that just stepped into racing over summer. Let me try to give an outsiders point of view.
Car isn't the hard part. I used a RTR BT-4, 3 other new driver used the SpecR chassis. We ran against XRays. Driver ability had more to do with anything them the car choice. All 4 of us were under $350 on cars. Only 1 needed to by a controller.
Only 2 of us had driven courses before. For most starting just making a lap without hitting rails is an accomplishment.
Time factor. Not everyone is willing or can commit to spending 4+ hours for a single class. I know that a low estimate on time.
Extra costs. Most understand that battery and charger, possibly controller if completely new, are part of the cost. It's the transponder. $80-100 to just try something is a hard expense. I know of at least 2 that wanted to try running over summer but wouldn't buy a transponder.