I'm skeptical of licensing as a means of determining ability.
No other engineering discipline uses licensing (with the exception of PE roles, for obvious reasons) to determine ability. Think about how mechanical engineers get hired, for instance. "What were some technical challenges you had in your last project? How did you solve them?" would be a couple of leading questions into technical discussions with a candidate.
Note that those questions are not specific to mechanical engineering: they are applicable to every engineering and software role.
In the interviews I have conducted, asking these types of questions exactly has generally given me a pretty good sense of the technical ability of every candidate, with no whiteboard session or coding homework required. It only takes 30-45 minutes, and I have also found that this amount of time is enough to get a sense of a candidate's culture fit as well.
Whiteboard interviews only test how much of a candidate's memorized corpus overlaps with the question presented; as a result, I find that process is only 5-10% as effective as a technical discussion. I want to know if and how (and how well) a given candidate thinks, not if they know the same things I do.
Code homework is only marginally better. Most (better) companies have a 90-day probation period anyway. After hire, if a developer is not performing up to expectations for a given role, they can be let go. This is exactly how it happens in every other engineering profession.