The united states is somewhat well-known for having an incredibly large amount of small regional airports, usually serviced by low capacity aircraft. So my question today is what is stopping manufacturers from designing single engined jets that can hold a capacity similar to a Q series turboprop (at most 40 passengers)? Such a plane could have a similar engine configuration to the S-duct of an L-1011 or any other plane with a tail mounted engine.

It's not like having 1 engine is a too extreme a limitation when flying above land, modern high bypass jet engines produce more thrust than ever before at unprecedented fuel efficiencies! So a single engined plane would have the benefit of less weight, 2 times less fuel consumption, and faster speed than turboprops. This would come at the potential cost of safety (a factor undermined by flying above land via flight paths that pass near multiple airports for extra security) while denying such planes service across large bodies of water (a trait that does not matter for medium range jetliners).

Of course, it's possible the limitation here is economical in nature, but the federal and state governments across the united states invest money into regional airports and aviation companies profit from considerable government aid so I am skeptical about the "lack of political will" scenario, as funding such an aircraft would make any political supporter look good (helps improve regional airports at less of a cost to the environment all while encouraging a competitive aviation market is a win-win-win)

I'd appreciate if you guys could build on this concept of single engine small capacity jet aircraft, maybe post photos of what they could look like if you have the time ^^
also sorry for not citing sources, I'll do better next time anons