To clarify, chains don't 'stretch', they simply wear between the pins and links, and that minute wear from each link adds up to a longer overall chain. so the chain does grow longer, but it does not actually 'stretch'.
That wear means the chain pitch no longer precisely matches the pitch of the sprockets, so they begin to wear to try and match that pitch. (so always replace chain and sprockets together, if one is worn, so is the other).
While its true that bicycle and motorcycle chains wear rather quickly (compared to a timing chain inside an engine that can last the life of the motor), think about the environment they live in. They are out in the elements, with no continuous lubrication source. Any lube they do get, tends to attract more dirt and grit, which works its way in between the pin and link, greatly accelerating wear.
Contrast that with an engine timing chain. It lives in a sealed environment, with a constant supply of filtered oil. Consider also the ratio of length to width between engine timing chains and bicycle and motorcycle drive chains. The timing chain is much more robust. Think about the load, all the timing chain has to do is spin the cam(s), and bear the load of the valve springs and all the friction points, while a vehicle drive chain has to bear the load of moving the weight of the entire vehicle and cargo up hills, from a dead stop, etc.
Stop & go driving was mentioned, but I’m struggling to see how the load on an engine timing chain would vary much between stop & go and steady highway cruising, except that the rpm’s will likely be higher from time to time during stop & go. That of course isn’t true for other internal parts of the engine, say rod & main bearings. More acceleration means more load, but all the timing chain sees is the load from the valve train and the rpm’s, it won’t care if you’re pulling those rpm’s while accelerating like mad up a hill, or the same rpm’s cruising downhill.
To be sure the timing chain WILL wear, but so does the rest of the inside of the engine. The question is did the designers of your engine build a chain that will wear out about the same time as the rest of the engine, or not? I’d bet that barring problems with metallurgy, etc, that most engine timing chains will outlast stuff like main & rod bearings. So who cares if the chain does wear, so long as it doesn’t wear out before things like your engine bearings?
Unlike a bike chain, where you’ll end up needing to change it out many times over the life of the vehicle, an engine timing chain should last until its engine rebuild time.