ADP seems to have a half dozen or more discrete variations on their payroll product, each with their own weird quirks. I’ve experienced some that were perfectly adequate. Some of them being trash also seems plausible.

> some of them being trash also seems plausible

I wouldn't call them trash. They're just absurdly powerful tools for moving boatloads of money in infintessimal increments. It's incredibly low-level financial tooling that simply outclasses any organisation without full-time finance and payroll departments.