Liquid "can't" rug or inflate the supply, but members are not anonymous and are very susceptible to governments (of course, it isn't really used so governments don't really care right now).
Is it always a given, that Liquid members are public, while Fedimint members private? But yes, I agree both have tradeoffs, public members are susceptible to regulation, private members create incentives for rugs and reputation gaming.
Ecash incentives are for the mint to inflate and rug.
Regarding verifying money supply there is some promising research with eCash, but still experimental.
Ecash is not Bitcoin.
Neither is L-BTC. With Fedimint you have the risk of rugging, with Liquid I think as usage and government attention increases, asset freezes are just a matter of time.
Liquid is useful as a "real-money" testnet for Bitcoin upgrades-- CTV, OPCAT, etc.
Makes sense.