Behind the scenes is China’s reluctance to forgive debt...
In the past under such circumstances, big government lenders such as the U.S., Japan and France would work out deals to forgive some debt, with each lender disclosing clearly what they were owed and on what terms so no one would feel cheated. But China didn’t play by those rules.
I feel there's probably some reasons they haven't become popular.
I could imagine a velomobile being preferable if you're commuting from a satellite town to the city, and the journey consists of a long straight road.
I'd definitely say they're worse for getting around the city, and their comparative advantages are bought at the price of significant extra overhead.