Another interesting point is that ease of opening the hatch was a tradeoff that was pushed back and forth by (near) accidents. Mercury had a pyrotechnic hatch r

Another interesting point is that ease of opening the hatch was a tradeoff that was pushed back and forth by (near) accidents. Mercury had a pyrotechnic hatch release mechanism. That triggered accidentally on Mercury-Redstone 4, which caused the approach to be changed for Apollo. The hatch on Apollo 1 had mechanical latching mechanism and was moved manually. Apollo 1 accident caused the hatch on later Apollos to have still mechanical latches, but easier to operate, and pneumatic mechanism that lifted the hatch.