Open source models are actually _better_ at structured outputs because you can adapt them using tools like JSONFormer et al that interact with the internals of the model (https://www.reddit.com/r/LocalLLaMA/comments/17a4zlf/reliabl...). The structured outputs can be arbitrary grammars, for example, not just JSON (https://github.com/outlines-dev/outlines#using-context-free-...).
Some want to consider results relative to cost, and some are interested only in how it compares to SOTA.