It's possible to order brakes on a single axle trailer, usually.
In my experience (towing a cargo trailer 15k-20k miles per year for 2 decades, plus travel trailer towing) my tandems' rear tires would pick up nails 4 or 5 times a year, whereas the single axles might find a nail once a year. I think the front tire runs over the flat nail, kicks it point-up, and it stabs the back tire. I had a couple of tires get destroyed because they lost air and I didn't catch it in time (now I run TST TPMS on my single axle's tires, though I haven't had an issue with a trailer tire pressure suddenly falling for about 2 years!). The only way I'd get a tandem is if I simply had to have the extra weight carrying capacity. The single axles have towed straight and true (proper forward-biased loading is important with any trailer) and I never have any sway. No tire scrub when backing tight turns, either.
