Probably because the last time they had szechuan sauce was as a promotional thing for the first Mulan movie. (If I'm remembering right.) So last time, they had months to work with in terms of prep work for rolling it out chain-wide. And last time, it wouldn't have been a huge deal - it was just a cute promotional tie-in for a popular kids-aimed movie, McDonalds did that sort of thing all the time; this was back in the era of web-rings, when there were fifty different search engines and only really rich people had internet access on their cellphone - the odds of a sudden flash-mob of people looking for a specific sauce to go with their chicken nuggets was....pretty low, back then. This time, they had...maybe a few weeks? If that? And the Szechuan Sauce has become at least a brief internet phenomenon because of the show, and it's a lot easier for people to find out which locations are participating. Add to that the fact that it's been actual decades since they had anyone make any of the sauce...and you end up with what we've got: a handful of locations participating, most of them without sufficient supply to meet the demand. Participation was probably an opt-in thing, and some franchisees may have gone "fuck that, we're not dealing with this nonsense". Plus, twenty packets of sauce per location suggests to me that they didn't manage to get production cranked up fast enough in time for roll-out. (I hate to suggest it, but I do wonder if - based on such a tiny supply - they ended up having to drag out whatever was left from the initial run. I sort of doubt it, but mainly because I'm pretty sure they wouldn't have hung on to limited-edition sauce packets for twenty years. Anything that was left after the original run ended probably got binned or taken home by anyone who was around to grab it.)
Random aside here kinda wild that rick n Morty had death stranding commercials Also first ep dropped like recently, I watched it, its neat Spoiler I liked the anthro universe forms, meh on the nazi thing (like idk it feels eh. Like id rather not with it but its there)eta just idk doesnt sit well given current climate. I loved their wasp forms, but I think like the anthro designs were great in general I do think the reference to morty on messages boards is interesting tho, cause yeah thats a real way that recruits young ppl into extreme idealogies I do wonder whats up with morty n Jessica being together and old, but I guess its more of a motivation than anything else. I did find the 'summer trying to get jerry to die early so she can take hot funeral photos' kinda silly Kinda sad we didnt get more of summer but eh its the first ep