My daughter is an ER nurse, was a paramedic and 911 dispatcher before that. She says that depends entirely on the hospital. That said, we had occasion last fall to make numerous ER trips, for myself & my daughter, and it was definitely NOT true then. Paramedics were seen several times transferring patients from gurney to wheelchair and placing them in the ER waiting room with the rest of us. The same happened when I took my husband to the ER in Texas this winter. I asked one triage nurse, and she said "non-emergency" patients were using it to try to jump to the head of the line and their medical director put a stop to it. So, it may have once been true, maybe still is in some places, but not so much these days.

Also, insurance companies have been known to decline to pay for the ambulance if, in their judgment, it was not medically necessary.