What would an american provider have done? Changed their pricing model for you?
At least they can say "we sympathize but it's not a priority" or "it's a medium priority but we don't have a concrete timeline" or at least recommend best practices/workarounds
You can be metered or fixed price. Mixing the two in the most inuintive way possible is a true innovation. /s
Other cloud based provider have the option to pay for your usage to the cent. I guess that innovation didn't reach the EU. /s
Most likely they are unwilling to let customers pay later without any guarantee that they're good faith and solvent. Maybe it is a cultural thing? It's only my personal opinion but it never struck me as unreasonable.
I have never had to prepay anything for Hetzner, not 20y ago for servers and not for the last 5-7 years for Cloud VPS. Maybe for recent-ish signups?
Some hosters support prepaying (for example INWX where I have my domains) but I am reasonably sure you could also do other forms of payment