RPM is correct here.
zypper does check the whole situation and acts accordingly, it will e.g. install extra packages when they are dependencies
It has nothing to do with dependencies. zypper does equivalent of “rpm --nodeps --force --noscripts” and evaluates dependencies and conflicts itself. In this case filesystem package has /usr/share with modes 0555 (r-xr-xr-x) while master-pdf package has /usr/share with modes -755 (rwxr-xr-x). So forcing installation makes this directory writable.
RPM allows directories “shared” between packages as long as their attributes are identical. Here attributes are different so RPM quite correctly refuses to install (without forcing installation). Zypper pretends to know better than RPM but does not implement this check.