Does shock stall occur at lower Mach speed than tuck under? If I got it correct, shock stall in subsonic airliners occurs at around M 0.81 and tuck under way after, at about M 1.4 when the lift is regained but CP is moved back to around 50% of the chord? Is that correct?

Speaking about that, does every modern airliner have Mach trim, in an unexpected case of reaching such a high speed of ~M 1.4, or only the planes intended for supersonic speeds, such as Concorde?
Thanks.