Why is it that armour, aircraft, and vehicles are all in 1/72 scale yet larger scales are not the same. Vehicles some ships and aircraft are in 1/32 scale yet armour is in 1/35 scale? Vehicles are also in 1/24 or 1/25 scale. I have not included the smaller scales as they mostly seem to be naval vessels.

In a nutshell: English measurements versus metric measurements, box size, battery and motor size (most early large scale armor was motorized) and the personal preference of the head of a certain eponymous model company based on those factors.

1/24 versus 1/24 is an example of English fractional measurement versus the decimal measurement of the Metric system. 1/24 is twice the size of 1/48 which is quarter inch equals a foot. The classic ship scale used to be 1/96 and 1/192 which fits in with fractions of an inch equalling a foot as does 1/32.

Sounds good to me.