eBay

"They are making more money on the tax and shipping and they shouldn’t be charging me for it."

- maybe, but they are handling the funds and dispersing funds to the IRS, and the shipping companies to make it easier for buyers & sellers. That requires management and attention, therefor money. stereo5 is correct, maybe eBay is not for you.

@ OP

That was part of the User Agreement when you sign up, so it's legal.

A little background around fees on shipping. Years ago, sellers tried to circumvent ebay fee system by selling an item at a very low price $1 and charge a shipping $1000 (for demonstration purposes) because ebay charges fee only on the Sell Price, not shipping fee. To solve this problem, fee on shipping cost was added.

In my experience, ebay has often charged too much for sales tax for my state.  When questioned their response was basically “we’re not going to change anything”

@cfa88

Now that was a well written, productive post that educates and enlightens. Makes perfect sense to me, and I would do the same. Thanks for the informative post. 
 

Best-

If purchasing an item from a different country, watch the conversion rate eBay offers to you. Perform a quick currency swap price  online. Every time I have checked before a purchase, eBay has undervalued the USD. Having the credit card company set the conversion rate vs eBay doing so saved a significant amount of money.