In particular, they tended to roll much better than Hot Wheels.
The "axles" were some kind of fine spring steel. The matchbox cars had noticeably less drag than other brands and rolled farther and more straight. The plastic on the wheels was more flexible and smooth.
I do think that some thought went into how these things rolled. Or maybe I am mis-remembering my childhood experiences? I guess I will never find out!
The older history is different.
I was already a Matchbox fan when HotWheels were first introduced: HotWheels invented the "give it a push and it rolls a good distance" type of wheels-on-wire-axles, slick enough that they could make the HotWheels race track with the spinning rubber capstan sending the cars all the way around the track. A Matchbox's wheels would turn, but it would only roll inches if given a push.
Matchbox was getting crushed in the market. Then a year or two later (a long time when you're a kid) they introduced the Matchbox Superfast line which had the same type of wire-sprung wheels, but they still weren't as good at rolling as HotWheels.
but being a child on-the-spectrum I was pretty upset by the whole thing for another reason, because Matchbox cars were realistic reproductions of actual car models (Maserati Ghibli); HotWheels cars were imaginary fantasy cars (Green Goblin or something), and I couldn't stand them, I liked realism and my favorite way to play with them had a lot of parallel parking... but HotWheels were better.
so the end of the story is... I hit puberty