To be fair (to an unfair policy): this "rule" from the manufacturers/suppliers isn't written that way in so many words, but the end result ends up being:
It might as well be!
A Wheelchair manufacturer won't sell you a wheelchair without a doctor's or therapist's prescription in your hot little hand (because they want to make sure they're not selling you something that will cause further injury, and open themselves up to a lawsuit).
But a doctor or therapist won't write you a prescription if your insurance won't cover it -- even if they agree that you actually need it (because they don't want to prescribe something that has the potential to bankrupt you).
And the reason buying a wheelchair costs enough to potentially bankrupt someone? The manufacturer has to figure insurance costs and doctors' fees into their overhead (at least, that's what they tell us).
A bit of clarificaton (after sleeping on it):
A Wheelchair manufacturer won't sell you a wheelchair without a doctor's or therapist's prescription in your hot little hand (because they want to make sure they're not selling you something that will cause further injury, and open themselves up to a lawsuit).
But a doctor or therapist won't write you a prescription if your insurance won't cover it -- even if they agree that you actually need it (because they don't want to prescribe something that has the potential to bankrupt you).
And the reason buying a wheelchair costs enough to potentially bankrupt someone? The manufacturer has to figure insurance costs and doctors' fees into their overhead (at least, that's what they tell us).
...And 'round and 'round we go!