That's the way it appears to be.

None of this is really making any sense, there's no consistency in the results. All of the items were from Bessey and all were made in China yet they were taxed at different levels. The items that had polymer parts had higher tariffs than the all metal item.
Recently, Amazon also went through similar machinations when I ordered another Bessey item. The item was listed at $26 on Amazon, when I added shipping the item went to $46 and then when I confirmed my address and I went to pay for it the item suddenly became $83. Needless to say...that item was also not purchased.
The lesson here is if you're shopping Amazon, it's best to put the item in the shopping cart first rather than just hit the Buy Now button.