TC started in the 90s. Tamiya basically defined the class with the TA-01 (a shrunken buggy), virtually all the other manufacturers copied the wheel dimensions, those that didn't soon changed to the 12mm hex, and the standard was set.
Off-road is different. The major manufacturers have been in it since the 70s/80s. There was very rapid development of the cars which meant that each manufacturer was pursuing various wheel mounting systems and various offsets to get the performance they wanted. The class matured with car-specific wheels being the norm. So as time progressed you had Associated with the pin drive rear and imperial bearings in the front wheels, Losi with a different offset on the rear wheel and a small hex on the front wheel (which AE later matched), Tamiya with a 12mm hex, Kyosho with a 12mm hex but a different offset, and plenty of other bizarre wheel fittings (remember the screw-through wheels on Schumachers and the two- or three-screw fixing on Yokomos?)
A little while ago almost every car had settled on the Losi-style wheel fittings (pin drive rear, small hex up front for 4wd, bearings in wheel for 2wd). A few cars have moved towards larger hexes since then, which is both good and bad - the hex is a better design solution, but it means that the wheels are becoming car specific again.
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