I am not an expert on lens design but my first thought is to wonder how a lens would know which range of brightness was to be which range of tones for me. The brightness of light is very relative to I guess a comparative perception, a phrase I just made up. The lens would have to have a computer chip in it to calculate brightness range and contrasts. As far I my non expert knowledge goes I understand that the lens designs are balancing contrast and resolution. The highest resolution lens is too low contrast. A contrasty lens appears sharp but actually doesn't have as much resolution. My other non expert idea is that the European lens designs like Zeiss Schneider and Leitz go for a bit higher resolution and a bit less contrast compared to the Japanese designs like Mamiya and Pentax are contrasty. If you want to tell me I am full of barn yard manure, I won't argue.
Dennis