That's just what log scales look like. The plots are variables which are exponents of a base of value ten. If you dump the base and exponents and just look at the value of the variables, the scale will be linear, e.g. (log)100 = 2, (log)1000 = 3.

"Is there any logical reason that group it out the way they do other than to save space?"

No, you are right - its to save space.

"Is there any logical reason that group it out the way they do other than to save space?"

No, you are right - its to save space.