As an ordinary rule of thumb, would it be safe to assume that no one should use a website that does not give a physical street address as their base.
For example, there are many on line book PRINTERS that will print your book for you; some give a physical address and others do not give any.
Any info is appreciated. Thanks

Very difficult to make sweeping generalisations here.
That's why the review sites, like trustpilot, as so useful..

Most websites are actually located in vast Datacenters that host MANY such sites not in someone's basement.

In fact many of then aren't even on their own server, except for the larger ones...most even share servers due to virtualization.

Kinko's and other copier places will print the book for you for a reasonable cost. They might even do a perfect (glued, like a paperback or phone book) binding. Or, for a stitched or perfect binding, call/visit your library reference desk and ask about the bindery service they use. Some of our patrons who wanted to rebind an old book or put together a new one used the same service that we did.

Do you have a cover? Are your pages properly formatted and numbered? Has your book been beta-read and edited? Maybe check Smashwords as an reputable online publisher.

As for a street address, my nieces got their book published by a small vanity press that charged them mucho dinero. It turned out the "press" farmed out the publishing work to a large printer that did this for other vanity presses, too. And the address of the "small press" was an employee's condo.