I always send bitcoin to those, usually about 50 cents worth. The address are not unique and you will see a dozen or more people send the requested amount (e.g. $800). Since those amounts are not unique and the addresses are reused, the scammer has no way of knowing if a victim paid or not. A victim has no way of notiftying the scammer that they have paid.
So not only is the scam obvious from the exotic claims (turning on the webcam, etc) but it is obviously a scam from the non-personalized payment.