IR Heaters do not heat the space the heat the surfaces, specifically the humans.
Basically it makes people feel warm by toasting them however leaving them on when there’s no one around is a waste because it only warms the surfaces so things get warm but not the air.
This makes it seem ineffectual but it really is just different ways to solve a problem. The reason they’re popular in pubs is it is impossible to heat the outside but it is possible to heat the people.