Why do car rental places have names that imply cheapness

It's really the only industry I can think of where you're getting a quality product and yet the company stresses "Budget" "Thrifty" "Dollar", etc.

Was it that a lot of these companies were founded in an era where price was the only factor (late 70's?) where as lately companies like Starbucks have found success in overcharging but enveloping the product in an "experience"?

It's not like Budget has worse cars than Enterprise - they're the same fleet essentially.