I worked for a medium size payroll software company. Payroll is highly regionalized problem - every state and city has different rules/taxes and very unique on

I worked for a medium size payroll software company. Payroll is highly regionalized problem - every state and city has different rules/taxes and very unique ones as well. Its often not so simple to generically describe a payroll tax and plug in different configs per region. Much hidden complexity that's grown organically over time as laws/taxes change (which they do!). A rewrite would be an archaeological dig. I would have to be paid a lot to take that problem on. It's also not trivial software to manage, so often it's outsourced as a service (run by humans) on top of software that cut the checks for your employees. Makes me think that the margins are low? I dunno. Modern companies like gusto are changing this