system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why isn’t strength training considered cardio even though it gets your heart rate up?

My heart rate goes up and I break a sweat, but it isn’t considered aerobic exercise and I’ve been told it doesn’t have the same cardiovascular benefits as aerobic even though I’m working up the same sweat, why is this?
gpt
It can be, if you do it for long enough. That's the main difference—aerobic exercise goes on long enough that your cells have to start manually respiring, so it is possible to get that done by doing high reps with low weight. It may help to think of jogging as an extremely high-rep bodyweight exercise—one that your anatomy has been so well-adapted to that it hardly registers as moving weight around. 

It just isn't efficient, and efficiency is what modern fitness is all about. If you only have an hour a day to train, you can burn lots of calories in the pool or build lots of muscle with heavy weight, so doing sprints or endurance lifts is seen as a waste for people who aren't specialized athletes or folks with weird job descriptions.