[greglindahl]

That's how it can tell you were very close to someone -- all of the other tracking apps do it that way, too.

[hailk]

I'm not familiar with app engineering, but wouldn't the location access be enough for that?

[greglindahl]

It's not app engineering, it's a comparison of GPS accuracy (especially indoors) vs a bluetooth beacon. Beacons work great no matter where you go.

I'm currently on the 11th floor of a building. GPS accuracy in the vertical dimension is much worse than horizontal. A bluetooth beacon will tell you if I'm in the same room with someone else.