It does seem like you should look more at the fitness tracking apps and not the cycling logging apps.

I've never looked into what my iPhone Health thinks I'm doing, but it's not using the GPS... at least the little arrow doesn't come on like it does for Google Maps or Strava. It seems to be working like a pedometer, and if it's picking up cycling it doesn't say so.

I'm pretty sure the reason Strava is such a pig is that it's loading maps all the time, same thing with Google Maps.