tl/dr
sorry i haven't read everyones comments and i'm sorry if someone mentioned this already.
i always figured that tape sounded "better" because analouge mediums have unlimited resolution.
with digital we have limited bit depths (16, 24, 32)
this applies to all digital mediums, tape, photograpy, film, etc...
this is one of the reasons that a film is still regarded better than digital for certain types of movies. nothing is truncated... information loss is the name of the game.
when you go digital the conversion process is an approximation of the original wave. the higher the bit depth, the more detailed the waveform captured.
this is one of the reasons you can hear an obvious difference between an 8-bit recording and a 16-bit one.
additionally try looking at the difference between a record and a cd, night and day.
these analouge mediums capture the waveform information in it's full resolution weather it be light or or any other type of electromagnetic energy.
in my opinion this is why a good film camera looks better than digital one.