I find that hard to believe. Why? Because at the vast majority of resorts, there is no way to tell who is going to what park via the buses. For instance...if at BW, everyone just mills around at the bus stop and then when the appropriate bus comes along, they move to the street to board the bus. So, there would be no way, even using cameras, to judge how many people were going to, say, MK.
If someone had to wait 90 mins for a bus to a park, there was some kind of huge issue. I'm not calling anyone a liar, but it's hard to believe. In over 30 trips to WDW, I have never waited more than 40 mins for a bus...and that was at park closing at MK when staying at Pop!! From a resort to a park I had my longest wait at AKL-Jambo House...it was about 30 mins from the time I got to the bus stop to the time I boarded a bus. And that time we arrived just as the DHS bus (the one we wanted) was pulling away.
If Disney were to install camera's at resort bus stops, and not dispatch buses until the stops were full, there would be a huge number of people renting cars...and Disney doesn't want that.