Actually the scare was in the early 70s (the 1971 Bon Vivant Soup case) which was scary because it occurred in commercially canned food where it had been extremely rare in the US. There are no shortage of food borne illnesses in the US, Salmonella, E-Coli, and Listeria have all been causes of many serious (including fatal) outcomes. Amtrak is subject directly to FDA rules and inspections, not local like most food serving establishments.
As to popcorn, that is a good point. Most establishments that sell quantities of popcorn either pop their own, or buy it in big bags and warm
it. The single serve microwave market is predominantly home/office and most of those microwaves even have a "popcorn" setting. More powerful commercial units overpower popcorn packages, often get a bad result unless you have a low power setting available. (not time, power)