I remember at the beginning of the pandemic state unemployment systems using COBOL and a lack of qualified developers was blamed as the bottleneck for processing claims. It was all over HN for weeks.
Changes typically require 7 figures, so they require a long lead time that coincides with the state's budget cycle.
https://www.fastenterprises.com/solutions/fastui/
Also, the cost of one of these replacement projects is about $80 million over 3 years plus 10-20 million a year maintenance. Averaged over 10 years, this about 2-5 times the cost of the old systems, depending on how you want to count.