Traveller

So I went back to this thing after quite a while, when testing all sorts of things started to really get on my nerves. After having manually created 55 custom peep groups, I am still no wiser than before.
I'm about done calling the bug as totally unavoidable, because every single scenario and peep combination I tried, the bug reappeared, sometimes sooner, sometimes later, - but it always will appear! So, I think it might be safe to say that nothing is certain in life, except death and the RCT3 elevator bug. However... two somewhat interesting results of my vigorous testing routines followed:
1) When a member or members of the group separate so that part of the group (even if it's just a group of two people) is or are on an elevator ride, and the other(s) are waiting, the elevator bug is more likely to appear. That much is certain. Nothing I have tried has prevented the bug appearing. I did create a large number of groups with only one person the group, but they would just as well get stuck as the other  groups.
2) Another bug I rediscovered, after having already forgotten about it, is that peeps can get stuck on the path cross-sections, in areas where path width is more the 2 squares! This bug also will appear sooner or later, if an area in these wide areas gets too crowded - often near areas where there a number of ride entrances and exits lead to the same path edge.
Here's a screenshot of this "peep traffic jam" made by someone else I just found on the net:

The "No-CD" hacked exe from GameCopyWorld, isn't a "patch", as such. As most of "No Disc" executables are simply just the original exe files, which has the DRM and/or forced disc check simply removed. I have personally never encountered a hacked game exe, which would have been "dangerous". Most virus scanners will give a false positive with these files, but that's what those messages are, false positives, because most virus scanners will simply detect that piece of code affecting DRM manipulation. Now, having said all that.... I do NOT personally recommend using these hacks, because they can contain issues affecting other features in the game. I too have the original RCT3 CD, and I did use the NO-CD, because it's so annoying using the disc, which serves no other purpose than to wear down my CD/DVD drive. Back in the day (late 90s-early 2000s) when I was working as a computer mechanic, our shop had a real surge in broken down CD/DVD drives - and at first we couldn't figure it out, because it wasn't limited to just one brand. Only much later on we discovered that some specific games which used a version of StarForce disc protection system simply broke the drives - when games with StarForce protection were played continuously long enough.
It's actually a really sad thing you can no longer purchase RCT3 from GOG, which I would always prefer to Steam version for ANY game - for one, because all GOG games are DRM free, and do not need a platform or network access, unlike Steam or EA's old Origin.