When Roe V Wade was overturned, there was a lot of talk encouraging women to remove period tracking apps in case the data could be used against them in the future. But the easiest way to track women is to simply watch financial transactions for abortion bills or services at a clinic. Even if you try to obfuscate by having a friend pay, if there are no private, cash-or-crypto links, it's trivial to connect the dots.
It was a reminder to me that being able too freely and privately make financial transactions is one of the most important and fundamental rights we have.