In my jurisdiction you get upto about $100k without having to register for VAT, but I wouldn't have a clue what tax implications I'd have if I took money and sold a service to someone from Peru.
40 years ago international trade was very specialised, especially trade in services, and companies had experts to help them with the legalities. The internet allows anyone to trade with anyone else, and tax law just doesn't keep up.
It's quite possible for a company or sole-trader with a revenue of $50k a year to be providing services to customers in 150 countries. That was unthinkable even 20 years ago. How do they ensure that they meet all applicable local laws (including buy not limited to tax)? What about if their customers are anonymous?
If I'm providing coding services to "Joe Blogs" who pays me via bitcoin or western union or even cash in the mail, how do I know he's not in Iran or Cuba and I'm breaking American law.
If I'm a developer in India and I do work with a customer in the USA and a customer in Iran (and customers in 50 other states), am I breaking US laws? Or Iranian laws? Or Indian laws? Not just tax laws, but economic boycotts, export laws, etc.
How do I keep on top of that even if I'm pulling in $50k/year in sponsorship, what about if it's just micropayments for my blog and I'm getting $500/year into my bitcoin wallet?
There's a third category you missed: amazon. They handle the transactions and even the fulfillment, but don't collect taxes on behalf of the seller in certain circumstances. A few years ago (before South Dakota v. Wayfair, Inc), amazon wouldn't charge sales taxes for certain third party sellers, especially out of state/foreign ones.
>In my jurisdiction you get upto about $100k without having to register for VAT, but I wouldn't have a clue what tax implications I'd have if I took money and sold a service to someone from Peru.
Hetzner (german hosting company) has a country/VAT selector on their site. If you select a EU country, you get charged 20% (or whatever) in VAT, but if you select US you pay 0% VAT.
For VAT I believe that many countries only have thresholds for sales from sellers in the country, or in another EU country. Other sellers owe VAT even on tiny sales.