Excuse the ignorance... but what do France and Germany specifically fear? That if Libra would become more popular than the mainstream fiat currencies Facebook could have more control over the economy than governments?
Not sure either, it's a legitimate question. A lot of people seem to find it obvious, but to me it seems like there is a lot of subtleties in why something is or isn't a threat. Bitcoin, Paypal, Ethereum, gift cards, and other online payment systems didn't get this reaction, it's just the Facebook-issued credits (which, for the record, isn't really a cryptocurrency, that's just the marketing department).