Us Warns Hidden Radios May Be Embedded in Solar-Powered Highway Infrastructure

I've seen a lot of products with Wi-Fi radios in them, because they come on microcontroller modules pre-certified to meet FCC requirements, while any device without a radio that runs at 1 MHz or higher, needs to be certified by the developer, which is expensive.

For only a few cents per unit, you can forgo spending tens of thousands of dollars and days to weeks weeks of time. It's usually the most cost effective option, for anything under around 100,000 units.

I've never seen cellular radio modules used the same way, as they cost tens of dollars instead of tens of cents, but Wi-Fi radios are still a security concern, due to the increased attack surface.