I have never been to a drive-in theater. I remember seeing one from the road when I was very young.
The problem now is that we’d have to keep the windows closed, idle the car, and run the AC the entire time (AC and protection from bugs is essential where I live even at night, during the summer and early fall). Is that even allowed?
I buy all my movies on BD, then rip/encode them to our media server (i.e., digital copies I actually do own), and we watch the movies + all the special features on our 65″ TV with access to our own kitchen and bathrooms. That works best for my family, I think.