For European, if Uber is registered in Europe and is the service provider, it would be the taxes of the country of the client.
"It is also this setup that also allows Uber to pay what their critics say is less than their ‘fair share’ of tax – Uber pays no VAT and, last year, only paid £411,000 in Corporation Tax."
https://www.londonreconnections.com/2017/understanding-uber-...