Sorry I missed your message. This group doesn't get much traffic.
Apache CLA is more widely accepted for sure, but most of the NumFOCUS communities don't use CLAs as they believe they prevent contribution. While CLAs protect organizations using the code, we have felt the risks to be minimal but contribution to be more important.
NumFOCUS codes are contributed from numerous individuals and we prefer the sharing of the copyright among those individuals. Once a person contributes a piece of code under a specific license, their intent is pretty clear, i.e. to share the code. Thus our users are protected from copyright infringement through these intentional acts of sharing to the code.
For codes that are based out of companies, e.g. TensorFlow or React, CLAs are necessary for protecting the host company. NumFOCUS is a small non-profit so there isn't really anyone to sue for damages, so once again their isn't much risk.
-- Andy