Yes they absolutely are. Firstly, HIV drugs work at the genetic level of the virus.
The HIV virus is very smart😁, once there's lack of compliance, the drug concentration is reduced in the blood, it gives the virus time to replicate and mutate (change it's genetic characteristics) so a drug which was effective before fails. This is common in children. HIV virus easily mutates, that's why patients on drug therapy do cd4 viral load to assess the effectiveness of the drug and detect drug resistance early.