The state monitors financial transactions primarily for tax purposes. I'm guessing a very substantial amount of data they collect is around payroll and sales.
Monitoring for taxes comes second.
All federal tax information for employees is self-reported by employers. There isn't a huge monitoring infrastructure in place—just required-by-law reporting of what people get paid. Getting paid with not-dollars doesn't change the system.
We don't have any system in place to show military spending breakdowns or get people upset about it or give people who are upset about it a way to influence changes shrinking it in the future.