In my congregation they had busses, but there wasn't a big push to ride them. They were arranged by the congregation, not the WTS. The only way it could've been a scam (as I'm quite certain that all involved in the case of my congregation were genuine moral men) is if there was a BOE letter saying that any excess contribution should be sent to the WTS WWW fund or something like that...and I'm not aware of any such letter. Though, with the new tithing arrangement I guess there wouldn't need to be, as any excess funds would be on top of the $5000 rainy day fund they're allowed and as such would have to be sent in.
In short, as far as I could tell, it is at worst an indirect scam, in the same vein of them saying that the congregation expenses are $xx per publisher per month, but encouraging those who can contribute more to do so in order to cover the costs of those who can't give as much. In most places, they'll get extra, but not a whole lot (especially if there's regular accounts reports). It's certainly not a scam on par with the disaster relief scam, where they fix peoples stuff using free labor, then pocket the insurance money that includes funds for labor.
Forgot to add, in our case, the busses were at least partially needed, because the WTS was too cheap to buy all the parking that is normally bought up when there's an event. In our case only the dedicated stadium parking was available, the other stuff (shops/restaurants/etc) was not (and I saw several who'd gotten towed for parking where they shouldn't)
Leaving quietly - you missed one reason why people don't mind the parking for games as much - the long walk ends with them at a fun event, not sitting in hell for 8 hours!