This website was prepared in 2000, citing many of the safety issues regarding prenatal ultrasound that are still present today.
A combination of misleading information, state and federal regulations not touching the matter, and that ultrasound side effects are an esoteric field of study which leads to this problem.
Unknowing parents love seeing their children, and unknowing practitioners do not have conclusive evidence that profiteering can cause harm. Not that all practitioners put money before safety, but many do in the case of fetal sonography. Some practitioners go so far as to intimidate people into getting more ultrasounds, which goes against the notion of informed consent.
One person who signed the petition at https://www.change.org/petitions/health-risks-of-prenatal-ultrasound-the-urgent-need-for-more-research-and-regulation left in the comments, “I have two children, and although my pregnancies were both high risk for various reasons (generally my health during pregnancy), I feel that the number of ultrasounds scheduled was excessive. I probably had close to 10 in my first pregnancy, and had at least two per week for the last two months of my second pregnancy. Scare tactics were used by my doctor any time I questioned the need for so many, including the claim that he needed to be “prepared” in case my babies were born with conditions that required immediate treatment. They were not. I genuinely believe that some OB’s see high risk pregnancies as a cash cow. Certainly mine did.”