At the resorts, many of the bus stops have buses for many locations stopping at the same stop. Since people don't know whether the bus they are waiting for is the next one coming, the 'line' often doesn't form until people can see which bus is coming next.
All the resort bus stops have a painted box outline with a wheelchair symbol inside the box at the bus stop. Guests with mobility devices can park in or near that box so the driver can see you.
If the bus coming is the one you want, let the driver know by waving, nodding, pointing or some other way that lets the driver know you want that bus.
Shaking your head would be the way to lt the driver know you are not waiting or that bus.
At the parks, different bus stops are set up a bit differently. The expectation is that guests with wheelchairs or
ECVs will get into the line with other guests.
A few lines have no 'opening' until the line comes to the front of the bus.
Many of the lines have a wheelchair 'opening' at the last turn of the line, in front of the area the back door will be when the bus stops. In those lines, the intent is to enter the line and continue in it to that 'opening' and at that point, wait where the driver can see you.
Some drivers my tell guests to go directly to that waiting area, and others will tell guests to use the regular line up to that point. If there are other guests already waiting and the line extends further than the wheelchair opening, guests who go directly to the wheelchair area will not be 'popular' with other guests (if that area is even accessible without going thru the line - some are not).
If in doubt, you can ask the CM who is directing guests to their stops.