The previous generation of vans is notorious for the latches freezing up with age and rust. I wouldn't be shocked if newer ones have some similar issue even with all the plastic parts.

But GM went to the metal for a couple reasons. 1 the plastic gets brittle as it ages. I hit a mirror with the handle on my second 2002 and it broke. 2 even if not brittle, it was fairly easy for people to pry and break to break into the vehicle. Not one of GM's better designs.

 

My 2013 Savana handle is plastic.

My old 2000 Astro door handles were metal. Very cheap metal. When it got cold, they broke too.

GM manufacturing has simply gone down the ****ter.