You are right, however, changing the signature would break the added test that was created (because it's tied to the plot signature for consistency). That's why I chose to implement it this way.

Looking at the polar code agian, we should rather modify the signature to become plt.polar(r, theta, fmt=None, /, **kwargs), as the call signature in the docstring already describes. The polar() function is conceptually not really a straight forwarding function. It generally does not make sense to specify polar(r), which technically is possible, resulting in a non-meaningful interger-range theta. Also the matlab inspired syntax polar(r, thetha, r2, theta2) is luckily almost never used.
polar() is not a wrapper, but rather a function that uses plot() internally as an implementation detail. Therefore, no signature consistency check is needed.

This will be for a separate PR, so please revert the polar change here. Technically, we first need to deprecate other signatures by checking that *args has two or three elements and if not warn_deprecated(). When the deprecation expires, we can write out the signature.

Reverted as requested 👍