<p>At our local Y, there are a number of squash courts with four walls with one door to get into the court. There is one court with a transparent wall and some room for spectators outside. I’ve played on the tennis team and matches weren’t monitored closely. You went out with your opponent with a fresh can of tennis balls and played your match. You called your own lines.</p>
<p>I would guess that there was stadium seating in front of the court to allow so many spectators to watch a match. They might also have a court with more than one transparent side which would mean that people on the sides could watch.</p>