There seems to be more and more foreign real estate brokers in the game these days and as our local brokers have to pay 15% on their commissions I think it is fair to tax the foreign brokers the same rate too.
As for tourism sector- this is an absolute "no go" and has already been beaten way back when by the use of NET rates. Instead of using Rack rates and % commissions hotels just work off of NET rates that are given to travel agents/wholesalers. This is how the terminoligy of NET rates originated.