How to encourage companies to drop Google's reCAPTCHA?

I strongly dislike Google's reCAPTCHA due to privacy concerns and the fact that it gives Google a way to punish users of other sites for using Firefox or blocking Google trackers. I am quite tired of being harassed on non-Google sites by having to click through countless street view pictures just to complete whatever routine action I'm trying to do. I have decided to start asking sites that use this hostile tool to reconsider.

What I am asking HN for are suggestions on how to make that message more effective and any success stories people might have from doing something similar. Right now my plan is to create a simple letter explaining my objections to the software and ask that they stop using it, then email that letter to any offending sites that I come across.

I welcome any suggestions you all might have and thank you in advance for the help.