ABA at its core utilizes an approach called "operant conditioning". The same approach is used to train animals, including dogs, dolphins, and all sorts of show/circus animals.
ABA at its inception used pretty horrific techniques including famously "shock therapy". And those techniques carried on for a while.
ABA was introduced at a time when most clients were institutionalized. ABA was definitely an improvement over institutions.
The person providing the therapy usually has only a high school diploma, and occasionally they have taken a 30-hour course (required in some states, not all). These RBTs, or "techs", are supervised by someone who has a master's degree and license (BCBA, Board Certified Behavior Analyst).
ABA at its core focuses solely on "behaviors", hence the name "Applied Behavior Analysis". The happiness of the client is not necessarily the priority (though there are instances where it can be).
Absent alternative effective approaches, I can understand the pros of ABA. When considering there are alternative EFFECTIVE approaches, ABA begins to look really cruel.
Unfortunately, insurances are slow to adapt to this, and therefore ABA becomes the default option because it is widely covered. The coverage for alternative approaches is still in its infancy (there are ABA clinics that masquerade as play-based approaches. Or is it the other way around?)
Please fact check anything I posted. I welcome any debate on this subject.