* Dealing with sensitive data is their core business, not a side concern. i.e. their customer base is security-conscious enough that they know incompetence on that front will kill their business

* Both of those specific services omit lots of specific identifiers in their data collection, and require you to go out of your way to send truly sensitive stuff to their servers

* By necessity, a technical analytics service gives you lots more control over where exactly it hooks in to your code.