Most of their workforce has been in their mid 20's and early 30's for the last decade or so; demographic-inspired change isn't coming because they have such insanely high turnover.
I used to work at Epic, but it was over six years ago at this point. Their entire stack at the time was MUMPS and VB6. No idea if that's still the case, mind you -- there were some modernization efforts underway when I left. Although from what my friends that work at Epic hospitals tell me about their software, it likely hasn't changed much.
And I almost certainly got hired there because I actually knew MUMPS from a previous job. Of the developers they hired during my cycle, every one of them was on an H1-B or fresh out of Carnegie Mellon or MIT; meanwhile I was a kid with a sub-3 GPA from a liberal arts school with a Political Science degree.
(If you do some light searching, you can find another famous story on TDWTF that I wrote about MUMPS.)
Do you not think that a major government initiative in HSR (which it would require, tax dollars or not) wouldn't come with the standard TSA security theater in tow?
At least for mid-level and higher positions, read the job description and know enough about every technology and concept they mention so that you could give an introductory lightning talk on it, AND why/when that technology is preferable over common alternatives A, B, and C.