Presence of electric brakes varies from brand to brand, even in the used market. My 1978 Trillium's curb weight is 1400 pounds and it came from the factory with electric brakes. It's not a popup, but certainly in that size range.
In the "new" folding trailer market, brakes as standard equipment in the 2,000 pound size range are a mixed bag. They're standard on "foldups" like the
Aliner, even the smallest (1200 lb.) version. Jayco's popups on the other hand offer brakes as an "option" on the two smaller models, though they're evidently included in some packages.
Link to brochure Since the smaller trailers are obviously aimed at the small-tow market (mostly cars with that over-a-thousand-pounds-must-have-brakes limit) I think that many new trailers on dealer lots probably have them. It's also pretty cheap to retrofit electric trailer brakes. We did it on a small trailer for less than a hundred dollars a wheel.
As for your own situation: multiple tugs don't require multiple brake controllers- as long as they're all wired with a standard seven-pin connector one can use a wireless controller like
this one that can be moved from one rig to another.
" Not every mind that wanders is lost. " With apologies to J.R.R. Tolkien