Not sure what EZ lubes were designed for, but large boat trailers have brakes.
What I have done is after a few years of doing the EZ lube, I pull the drums and check the brakes, then clean and repack the bearings and reinstall (naturally using new seals), and add more grease.
Just make sure to ALWAYS use a hand pump grease gun, and spin the tire/rim while pumping in the grease. This has worked for me with no problems.
As for cars going 50K miles between brake jobs...that mileage is determined by vehicle and driving habits; however, on every vehicle I have owned for the past many years, there is NO bearing repacking. The bearings are not re-packed with grease or serviced as a separate part. If the bearings go, it is a complete hub replacement since the bearings are sealed in the hubs. And I believe that is true for most vehicles anymore.
Trailer: Lifted 228BH, heavy duty springs and Yokohama tires
TV: 2016 GMC Sierra Z71 4x4 CC, SLT
Spare TV: Two Alaskan Malamutes
Living somewhere in ID; previously lived in Moab UT; previous to that, don't ask!