 with a population of at least 10 million people. 

"Flying cars" are herein defined as vehicles which are legal to operate on the roads of the country, and which also can be operated as legal aircraft in that same country. 

The two operations modes are not required to be covered by the same license. No type certificate, production certificate, or equivalent is required (although they are expected and hoped for). Fleet operators renting vehicles out to the public would qualify if the sales quantity is met.

An example of a "yes" resolution in the US would be a street-legal car which is also legal to fly under 14 CFR 23, 25, 27, 91, 103, or equivalent, and can be operated by anyone with a driver's license and appropriate flight certificate (or none, in the case of §103 and/or potential self-driving capability).

This question is focusing on sales because some street legal flying cars already exist in 2023, but there is no widespread adoption and it's not clear when/if mass-production and adoption of flying cars will arrive.

Hopefully the resolution criteria are clear enough; please provide recommendations if any further clarification is needed, and I'll review and add to the description.