Well, the assumption is that we're not going to have an in-rush of
volunteers, so in many cases it will be "one of the existing chairs
is asking for re-affirmation and the WG is happy" or "one of the
existing chairs is stepping down, and the WG is fine with the single
volunteer for replacement".

We do not want to spend large amounts of precious WG time on voting
with paper ballots, counting, etc. - which could easily take half an
hour or more.

So, we go for "the participants agree on a candidate, in whatever form
this will be expressed (humming, show of hands, withdrawal of the other
candidates, ...)", and if that turns out to be non-working, we'll have
to come up with a formal tie breaking mechanism by the next meeting.

(This actually was one of the reasons why the WG chair collective could
not agree on a common policy.  Half of us wanted something lightweight
and not time consuming, while the other half wanted "something more
formal").