When I ride my indoor trainer - an old TurboTrainer type of unit, with no smarts of its own - the session shows up in Strava with a short but non-zero distance and a very short duration. My best guess as to what's going on is that the distance is based on GPS jitter that makes it look like my position occasionally changes by a few feet, and the duration is a "moving time" based on those position changes. When I ride the trainer for 30 minutes, with of course an actual distance of 0, Strava typically shows a distance of about 0.1 mile and a duration of about 3 minutes.
Tagging the activity as Indoor Cycling or changing the activity type to Virtual Ride has no effect. The same activity appears with the correct duration when I upload it to Garmin Connect, but it does also show the very short distance.
To make this a post about features, here's my suggestion:
When a ride is tagged as Indoor Cycling, and has a route that's confined to a radius of 100 meters or less, and has a distance that works out to an average speed less than 1 km/hour, make Strava smart enough to recognize that the athlete was actually riding in one place for the duration of the activity and that the "moving time" calculation should be skipped.