You're mostly correct that the older tech is the bulk of what's been sent, but there have been lots of batches of newer tech that the US has delivered. [0]
These newer companies (Anduril, Skydio, etc.) do it for a few reasons. Some are obvious: they get paid and their systems have a chance at influencing real-world events that the leadership & rank-and-file employees might care about personally.
But from a pure product development perspective, fielding these systems is a valuable test opportunity. You've built a great drone but you're not sure how it'll perform in a GPS-denied environment with S-band radio completely unusable? Russian Electronic Warfare teams are happy to curate that environment for you.
