No it's not required by code. Possibly by a local jurisdiction might require it above and beyond what the a17.1 code requires, like KSNY said new York requires it. Ive got a bunch of jobs that were modded or installed in the last couple years and our area is on the 2013 code currently, none of them have load weighing. I'm not sure if the 2019 code will make it mandatory but I'm pretty sure the 16 code did not. Seems silly if they did since it's not a safety improvement. Possibly a ride quality improvement. But I guess even that depends, it's not a given your ride will be improved with load weighing. All ecospaces have it. I have a hospital of MCE iboxs at 500 fpm 5000 pound capacity cars gearless torin machines with no load weighing and they run much better than ecospaces. And I've never noticed any issue with rollback or jerky starts with empty car or loaded up.