VanDork, the financial practices of Smith Industries are obscure at best. Does SI have an exclusive arrangement with the Naperville PD, or do they market their products to other agencies? Because if the NPD is their only customer for Diet Smith’s inventions, there’s little margin for profit (barring some massive corruption, which presumably is off the table here).
It seems likely that Smith develops his inventions with an eye toward the market, and uses the NPD as a testing ground. It’s hard to imagine a situation where one police department comes to Smith and says “We need an electronic crowd-control gizmo for riots.” If Naperville has enough riots to justify that, then the city is doing something wrong.