Re: ultrasounds - yes, stages of pregnancy were determined by best guess in pre-ultrasound days, but sometimes they were wrong, and sometimes seriously wrong.
Back in the late 1940's, my mom was ill for some months, losing weight, horrible bleeding, other problems, and the doctor determined she had a fibroid "the size of a grapefruit" that needed to come out.
He opened her up, and oops! There was a baby. Plus a fibroid, but still, he had not expected to find that baby there. It was about 5 to 6 months' gestation.
He removed the fibroid, stitched Mom back up, the baby was born and died within hours the next day. An ultrasound might have really, really helped in that situation, so the doctor would have known what to expect.
Then years later, when she was 51 and newly remarried, she had that ol' familiar feeling again, went to the doctor, and he said she was pregnant. Test came back negative, but he didn't believe the test, swore up and down she was pregnant.
Turned out THAT time, it was only the fibroid, which resolved on its own when she shortly thereafter went through menopause.
An ultrasound would have been nice to have then, too.
I can't see any problem whatsoever with requiring an ultrasound, although obviously there's a problem with requiring the women to pay for it if they can't afford it. But the procedure and the method of payment seem like two entirely different issues to me.