This is mainly due to new technologies and techniques in dyeing and hair care. Also now there is a trend for health, heating the hair during the dyeing process causes additional harm. But as before, climazones are used in many salons.
Probably the cost of professional equipment, although modern program-controlled dryers are much more comfortable for hair than a jet of hot air from a hair dryer. Economically, extra costs are not added to the service cost.