What Tolerent and Dabbler and the rest of them said.
As I understand it, before the lathe leaves the factory, it is tested for alignment. But the manufacturer first levels the lathe using the same procedure that is outlined in the lathe owner manual. Then if it passes the tests, they send it out for sale. You may even get a test card that shows you the tests and that the lathe passed.
So, theoretically, if you achieve level as outlined in the manual, then you have put the lathe back to the same position as when it was tested and passed at the factory. It should be properly aligned, and it gives you the best starting point when you set it up in your shop. But, recognize that things may change during shipping and handling and jostling to get it into position. So after leveling, we take additional test cuts and make adjustments to get it properly aligned and cutting straight. This is also part of the set up procedure set forth in most owner manuals; they tell you to do the two collar test after you have leveled the bed.
I don't know if any of this applies to the asian imports, but it should. Badly worn lathes are another story altogether.
And I don't know how they do it on ships, although clearly the lathe need not be level in use. There must be some tricks in setting it up. But most of us aren't on ships, and have the ability to set the machine up as the manufacturer intended. Is there really any resistance to doing that?