And items like tractors and construction equipment come in several sizes...so that Matchbox bulldozer that is 1/64 can be used for HO with a few modifications.
Hot Wheels, Matchbox, Corgi Jr. and etc. did not stick to any scale. A Chevy Monza was the same size as a Fleetwood was the same size as a Peterbilt. They sized them to the matchbox, bubble pack, whatever. Everything was close to the same length. Occasionally a bus or big truck would accidentally come out in perfect HO scale.
Peeked my long-time interest found this discussion . . . Can still buy Thunderjet cars "uknowwhere" and the 'ole style Aurora HO R.R. crossing track with straight pin connectors & center 'u locks' can still be found as well. Spoiler: YIKES! Found a 'retail' site for $99? Aurora Model Motoring #1522 - 9" x 9" Railroad Crossing HO Scale Slot Car SOLD $45.01 7 Bids, $7.50 Shipping (post edit: Was searching "seller other items" & found an antique HO 1/87 car here)