Parents research for weeks and decide on three things
An ABA inquiry is not an impulse. A parent gets a diagnosis, spends weeks reading, joins two or three local Facebook groups, and builds a short list before contacting anybody. By the time they call you they already know what ABA is, and they are screening for insurance acceptance, waitlist length, and how far they have to drive twice a day.
Pages written to explain what applied behavior analysis is get read by people who already know. The pages that produce calls answer what parents cannot find elsewhere: do you take my plan, how long is the wait, what does a first week look like, do you run center-based or in-home, and what happens when my authorization runs out.
About 1 in 31 eight-year-olds in the US is identified with autism spectrum disorder, per the CDC's most recent surveillance data. Local demand is not the constraint in most markets. Being the center that answers the question a parent is stuck on is.