For the same reasons fortune 500s will spec the same for their office workers. Labor is expensive compared to hardware. It is often cheaper to spend a little bit more on hardware to avoid supporting multiple configuration, exceptions, more frequent updates, support tickets from power users, etc
If you pinch pennies buying a spec that exactly meets today’s needs, and next year MS Teams releases a new update that requires more resources, you don’t want to buy a whole building full of new computers.
You seem to live in a bit of a bubble, personally I've never seen anything other than penny-pinching on corporate laptops and everybody everywhere complaining about the same.
(I don't mean that IT departments hand out bottom-of-the-barrel plastic laptops which break every five minutes, but rather fairly low-spec Thinkpad/HP/Dell business laptops with just enough RAM that their bloated Windows 11 installs are barely not swapping when idle and just enough SSD space that Windows Update doesn't fail)
Border Patrol’s IT department more forward looking than the rest of the government..? sign me up! I’ve been using the same laptop for nearly 5 years now. It’s painfully slow and does not meet the needs of the latest Teams updates.