[Tagging] default value for "oneway"

[Xavier Noria]

Hi,

The default value for "oneway" is "no" for most types of roads. That
is, if the attribute has no value set, "no" is assumed. Which is the
rationale for that default?

In the European cities and towns I know the majority of streets are
one-way. For example Barcelona, or Madrid, or Paris. In such areas,
are contributors expected to annotate "no"s rather than leaving the
tag blank?