The problem is that there's absolutely no incentive for doctors to act ethically. You don't win any points for ignoring drug company marketing.

Vendor marketing exists in all fields, technology included. The difference is that when I'm spending money on a vendor as a tech manager it's coming out of my budget. I have an incentive to make sure that the spending is intelligent and the solution is effective.

Where is the incentive for doctors to do that? They're spending other people's money on other people's problems.