Honestly I'm torn here. Twitter is a good example for your specific scenario here, but the US government, at least, is absolutely not trustworthy for building and running infrastructure.
My wife is in grad school and we're taking on loans, part of which involves FAFSA. I spent a mildly infuriating hour or two the other day trying to figure out our next steps, in large part because every single HTTP request to studentaid.gov was taking a minimum of 8 seconds. Meaning literal 2-minute page load times, which makes an already confusing situation about 10x more frustrating. And then when things did load, a significant portion of the time, there were significant bugs like important "notifications" appearing and disappearing, or not being clickable and just a "figure it out yourself" type deal.
The way the system works, getting multiple contractors, etc, which I've been a part of as a contractor before, is just destined for failure. Maybe it works for NASA rockets and defense equipment, historically, but the process fails us when it comes to building tech in a significant number of cases.
I'm not sure what the right answer is. Maybe just open source standards, software, and protocols. At least in those cases, you stand a chance of someone who knows what they're doing helping out when something goes wrong.