My guess is mainly that it's not sexy, it's a fairly niche thing. VC will look at it and say "what's your moat" until someone bites and decides that you do have a moat, at which point you'll be like Transfer Wise (now called Wise), basically an old product pretending to be innovative.

I bet it could be done, just needs someone to take a punt.

One could imagine a load of such niches. Come in, act like you're doing something new, get investment, capture market.