This strikes me as an area where legislation could have a significant impact. It's an area where there is absolutely no economic incentive to do the right thing. It seems similar to the way email lists and spam were back in the early days of the internet. Based on my observations, the CAN-SPAM act requiring automated mailings to have an unsubscribe link actually seems to have been fairly effective at improving that situation. Granted, there is still spam, but the legit mailing lists are a lot easier to opt out of than they used to be. Perhaps some legislation relating to terms of service agreements could help with this problem?