tudorordering stuff online
PriorityMotifSome places don’t charge tax on the shipping so you’re paying less if you don’t choose free shipping.
In most places the tax is included in the price and often mandatory because nearly every country in the world can figure out a way to do exactly that.
Some States have exemptions on shipping charges. So you pay less sales tax if you pay $25/$5 over $30/free.
States and localities have different ways of handling sales taxes.
Not everything is about the US though
Plus, if they sell to people in the EU they need to charge VAT anyway on the shipping. Some exception apply, but you as a person will not run into them.