Decisions made by those shaping this hobby before us have dictated what we have today.
Historically, car stability in building miniature railroad equipment was an afterthought.
As Bill Donavan writes in his IBLS article mentioned earlier by pat1027 and oilcan,
park trains designed with the goal of giving a person a “ride’ were built to accommodate that objective.
Reference again here: http://ibls.org/mediawiki/index.php?tit ... -On_Trains
When it comes to the efforts of the industrious hobbyist building within their own means,
working in narrower than park gauge sizes, the story winds a little different.
Tracing far enough back into the past related to miniature railroading, the idea of actually getting aboard
a small moving train was one of personal challenge or novelty and not necessarily about a stable functioning ride.
Early emphasis was focused on building the locomotive and getting it to “move” on its own while rolling stock to ride on, was a lesser.
Today, the straddle type car design could be labeled a “safest” car for adults as mentioned in the topic but not so much for little people.
The straddle type car safety factor or effectiveness of actually being a SAFE riding car ranks quite poorly for small children.
Proof of this statement is pointedly illustrated in one of the earlier photos posted in this thread.
Scroll back to the picture and note how there's an older person holding on snugly to each small child riding the straddle type cars.
It reads like there are some good ideas here to further improve its design though in combating the top heaviness factor.
Interestingly, a tank car (those built with a center sill and modeled walking platforms for placing one’s feet) could be viewed as a first generation straddle type car. I fondly remember from childhood (1960’s) how there could be a fight over who got to ride on the tank car if someone didn’t get to it first.
Noting to Glenn who started this conversation, you have a [luxury] because you’re working in a larger gauge.
You have more freedom to push the teetering limits and do not have to consider the stability issue the way those
working in the popular ‘7’ and smaller gauges have to manage.