Inconsistent heart rate display on iPhone for non-cycling workouts

If I am doing an indoor cycling workout, my heart rate and other metrics, appear on my iphone. This is great, so I don't have to keep looking down to wait for my heart rate to get checked. Why, oh why, can't this be done with all of the other indoor workouts? Does apple not do elliptical training? Do you know what a pain it is to have to check the watch to see where you are at in training, especially with indoor rowing??

Seems donkey to have to always use indoor cycling to use this feature.

[Re-Titled by Moderator]