These are/were the biggest carpet cleaning franchises 40 years ago:
Chemdry
Coit
Domesticare
Duraclean
Rainbow
Servicemaster
Servpro
Stanley Steemer
(I know I likely missed some, but I want to get out of here as soon as the fog clears this morning)
Most of them migrated to become restoration organizations, with carpet cleaning having become an afterthought. Some no longer exist, or are now small.
Stanley Steemer, while also now in the restoration business, seems to be the only one who has stood the test of time and who still out markets everyone else.
They promote hard surface and air duct cleaning as much, if not more than carpet cleaning, and look to be entering the in plant rug cleaning industry with strong commitments there too.
Most cleaners find them to be unlikable, but when they run an ad, everyone’s phone rings.