Google owes its existence to the open web, but today, its technological “innovations” have much to do with locking users into a “walled garden.” The latest of these is “reCAPTCHA Mobile Verification,” an experimental initiative that will let companies block users if they are running independent, "de-googled" versions of Android. These “indie Android” versions are favored by people who want to protect their privacy and their attention by blocking trackers and ads.