“Are there different shittos about chalav yisroel”
No. All agree there is a takanas chazal. There is disagreement whether the commercial milk sold in the USA under government oversight and regulation satisfies this takanas chazal.
“or do people just make up their own rules.”
Personally, I dont know a large enough percentage of “people” to state one way or another what “people” do or dont do.
“chalav stam”
the proper term is chalav shel hakompanies – IE milk produced under government oversight and regulation.
“And what about products on dairy equipment only. Is that considered chalav stam.”
You mean, chalav shel hacompanies, right?
“On a side note, I am amazed the number of people who no longer or who never have adhered to chalav yisroel.”
I am hard pressed to find anyone who does not. I am familiar with people who drink milk labeled chalav yisroel, and people who drink chalav produced under government oversight and regulation which according to their poskim satisfy the takanas chazal.