Ye but the bus driver is in control of how many board it. Honestly I can't remember the time I rode one of the trams but I'd memory serves it stops and people start boarding it, is there a line or do you just find a spot?
The trams have a queue of sorts. Hopefully, I can explain with some clarity. The trams run in a designated lane that is very clearly marked. When the tram stops, it stops in a designated area that has clear line markers painted on the pavement. Along where the tram stops, there has always been (or at least for a long time before the pandemic) a very bright wide yellow line. As the tram approaches, CM's repeatedly announce to, "STAND BEHIND THE YELLOW LINE!" until the CM tells them to board. When the tram fills, they tell people they must STAND BEHIND THE YELLOW LINE! until the next tram arrives.
At the park exits, designated queue rows are marked for people who want a tram back to their car, but I don't think queue lanes are marked in the parking lots themselves. They could be added, but then the trams would only be able to use those specific pick-up/drop-off areas. In the past, they only drove in the tram lane, and usually aimed for specific parking rows, but could drop people off anywhere along the tram lane.
I think, currently, the parking lot CM's are - in the morning- temporarily, using every other parking space. After families have time to unload, the CM's THEN fill in the every-other empty spaces. (to help with social distancing).
These days, parking lots don't get particularly full, and walking would not be particularly significant for many folks. It could, however, be a problem for people with mobility challenges. People who
really know WDW can use the drop off area, but the parking lots attendants don't make that an easy option. When people enter the parking lots, they are funneled into a specific designated lane of traffic. The traffic lane is bordered with cones and often CM's waving their arms. If anyone tries to go a different way, the CM's will pretty quickly let them know they do NOT want anyone going a different way. If you know you can drop off a disabled guest AND you advocate forcefully, they will permit you to use the drop off area, but in my experience, you often have to insist. It depends on the CM, unless you specifically have handicapped permit plates.
People who aren't very familiar with WDW (i.e. most people) likely wouldn't think to ask if they can do a drop off, especially if they were at all expecting the trams to be running.
And let me add: folks who attempt to do some research before they arrive, will find many WDW information sites are currently offering outdated, pre-pandemic information. It took me 2 seconds to find a WDW information page saying WDW has trams- including pictures of said trams - but no indication trams are NOT currently operating. Ugh!