Why all discussions about healthcare reform revolve around money to pay for it? I am sure this is the wrong side of it. Whatever money you pay, you have a limit

Why all discussions about healthcare reform revolve around money to pay for it? I am sure this is the wrong side of it. Whatever money you pay, you have a limited supply of doctors. So in the end, more money just raises prices, redistributing who gets which care, anyway. Why not start with supply side? Automatically recognize diploma of doctors from all developed countries (you may start with a limited list - very rich countries with life expectancy higher than U.S. - start with UK, France and Germany, add a few more if it's not enough - no one can say that their doctors are not 'good enough') - and make them instant immigration papers - literally, hand out green cards right at the airport on arrival. Millions will flock and quickly saturate the market. Then you will not have a problem with either new single-payer, or old system.