Otherwise how does a non-kyc crypto card makes sense with a custodial wallet and what triggers the service provider issuer to freeze your card or crypto if they don't know who you are to begin with

Yeah ! They don't know who you are but so far you're using their service they own your coin and can freeze it at anytime..
This makes them custodial over your funds as well so far they hold they for you and it's even much more easier to scam you if it's a fake provider or deliberate actions because you have nothing to show for , nothing tied you your account other than whatever they offer you..
Lastly, their service maybe regulated and if they notice any suspicious activity your account could be freeze anyways and you could have a low chance of recovery since you don't want to reveal your identity in the first place..
Only kyc crypto cards are regulated? Regulations says kyc is mandatory right? So that means non-kyc crypto debit cards are all scams because they are non-regulated? You know which crypto debit cards are officially regulated from the Trump's administration?