The thing about public transportation, is that incidents can occur through no fault of a rider/passenger. Therefore an extremely high standard of safety is required for operations and management of public transportation, since in order to attract customers to use that transportation service, you have to ensure they remain safe and and transported reliably and consistancy, and that the customers come out the other side unscathed every time. The idea of passengers getting injured or maimed on public transportation through no fault of their own, other than that they wanted to use a transportation service and they hopped on a transit vehicle, is cause for a major public safety concern.
I tend to agree in part with this, in that a public service, of any type, inherently needs to inspire continuing
confidence in its patrons. Once you lose it, you start to create
anxiety in your patrons, and they will start to look to other options. Be that an airline and it's aircraft, the public health system, a restaurant, or the MBTA. Granted, the T is an essential government service at limited risk of being shut down, but it's lack of ridership is likely corelated with all this. If we use aviation specifically as a high-consequence, high visibility example, There have been studies, polls from the 70s DC10 incidents to the more recent 737 Max - in 2019, just after the maxes were pulled, 20% said they'd be avoiding the Max even after it's been fixed. Losing the confidence of your customers is a big problem - and only through the passage of time and the reality of price and convenience shopping consumers has that mostly been alievated today, at least in the US. A restaurant may never fully recover from a mass food poisoning incident, and the Ford Pinto's "Unsafe at Any Speed" thing has stained that car through today - reputational damage tends to be extremely long lasting.
Even today Boeing's public image is under lasting public scrutiny of it's management practices, and has not yet fully recovered - and the big recent 73M orders have been notably domestic. That trust has not been regained in its entirety. It's why the aviation market is so tightly regulated, with safety a priority - if you want people to trust stepping into a pressurized aluminum can at 38000 feet, something many are already anxious about in the first place, you need them to trust implicitly that they will step out on the other end. The FAAs dual missions are promoting safety and air travel - they're, in truth, two sides the same coin.
At the same time, that confidence/anxiety condition isn't limited to safety - it's also performance, reliability, ease. Staying with the airline analogy - generally, people have little to no qualms flying with Delta, or the other legacy mainline carriers. But Spirit? Frontier? Ryanair? Their cheap tickets are just enough to offset the discomfort, risk of operational catastrophe and lack of customer support.
Basically, once you have something that inspires
anxiety in your patrons instead of confidence, you've got a job in front of you to fix it. And sadly, the media tends not to be on your side - after whatever major incident first precipitates that public anxiety, they tend to continue to fuel it by further publicizing things that otherwise may have been just a footnote in a report. That's not to say these things shouldn't be subject to public scrutiny, but it tends to create a bit of an anxiety echo chamber. It's cutting through all of that negativity, with a period of sustained, demonstrated performance with little to no bumps.
In the MBTAs case, the series of incidents that led to the FTA SMI, and the SMI itself - hardly inspire confidence in the system being safe, and we're lucky it's yet to result in significant passenger fatalities. And yes, the speed restrictions probably do help prevent an accident that will actually cause passengers to feel deeply unsafe. Most people are inherently risk adverse - you don't want to descend into the earth to ride a subway knowing it's at risk of breaking down, or derailing, or any manner of incident - you want to feel safe, comfortable, secure that you will get to your destination. And while the recent safety incidents may have dissuaded some from stepping aboard a T train again, it's not just safety - its also passenger anxiety about "will I get to my appointment on time," and "am I confident that I can get there without having to deal with a bus diversion?" If that doesn't yield a "yes", you're likely to choose another mode of travel. I think in too many cases the answer is no, and that's the problem that Eng needs to solve.