Ah the ole double tip huh? From our perspective that kind of helps make up for those that don't tip, or those that do but accidentally take the voucher they signed (!) but I hate that it happened to you and definitely feel that all "auto-grats" should be disclosed, and people need to be aware that practices and norms are likely going to be different when they travel and therefore read the fine print. Or when in doubt just ask.
Thanks so much for helping others with your Steemit post (which I also upvoted) - good research way beyond the realm of restaurants that people will want to know.