About GOG not charging VAT, I looked through their website for any possible explanation and they do charge it. The full price you see on the game is also the tax. Its a nice mathematical trick they did there.
https://support.gog.com/hc/en-us/articles/212632089-User-Agreement
"6.4. All prices are visible in the product catalogue page. They’re inclusive of legally applicable sales taxes/VAT."