It's a matter of economics - the entertainers cost $$$, while goofus Karaoke cost $.

I remember, back in the early 1970s, bar bands were getting paid a whopping $200 per night. And then in the 1980s, they were getting paid a whopping $200 per night. In the 1990s, only a one man band (or DJ) could make a living on $200 per night. In the 2000s, it's a downloaded mp3 file from a "live" {via webcam} entertainer ;-)