They are paying for R&D and marketing. Even if you subtract out the difference in marketing budgets, the US is still paying for a disproportionate share of the R&D.
Moreover, ban drug marketing if you like, but keep in mind two things. One, the marketing is primarily so "worthwhile" because of the price insensitivity. Patient requests equivalent but better-advertised drug even if it costs $75,000 more dollars, when they're not the one paying. So fix that and the marketing budgets drop along with drug prices. Two, marketing increases the number of "customers" by more than the cost of the marketing (or why do it?), and the extra money is what both encourages and pays for more R&D.
Moreover, ban drug marketing if you like, but keep in mind two things. One, the marketing is primarily so "worthwhile" because of the price insensitivity. Patient requests equivalent but better-advertised drug even if it costs $75,000 more dollars, when they're not the one paying. So fix that and the marketing budgets drop along with drug prices. Two, marketing increases the number of "customers" by more than the cost of the marketing (or why do it?), and the extra money is what both encourages and pays for more R&D.