This small mistake (and it is initially small, just catastrophic) is a system breakdown, not necessarily a staffing breakdown. Though staffing is definitely a wider issue in the NAS.

Edit to add: looking at this incident closer it appears LGA was busy enough to make a single tower/ground controller an obviously bad plan. Still, systemically, there's enough low hanging fruit here, like ADSb in for the airport trucks or hold short line guard lights. I hope the takeaway isn't just "don't have controllers make mistakes".