Well, it wouldn’t be a 2-3 hour wait to leave the airport. A 3 hour time estimate would be from the moment you step off the flight to arriving at a park or restaurant. The general rule of thumb is to allow 3 hours from flight arrival to something you’re trying to schedule like an ADR or a FPP. Most people give a 1.5 to 2 hour estimate for the time it takes to get from the plane to your room. That includes a lot of fiddly bits on either end that you’ll have to endure no matter what your mode of transportation is - picking up luggage, walking through the airport, room check in at the resort, walking to your room, etc.
The buses leave when they’re full, so the driver might be able to give you an estimate. There’s a whole fleet of them, and when you go to the MDE area they scan your magic band and point you towards the one that’s headed to your resort. If it’s a busy time of day, you’ll get straight on the bus and everyone else on the bus will also be going to your resort or maybe one other one. Once the bus is full, they leave. It’s about a 30 minute drive in a bus or your own rental car, so that’s a chunk of time that doesn’t depend on your mode of transportation. If your flight lands at a less busy time they’ll probably put people from multiple resorts on the same bus so that they can fill the bus more quickly. You don’t wait as long to leave the airport, but then the drive will take more time because of the extra stops. Does that make sense?
(Edited to correct the airport to WDW driving time. I looked up the right time.)