Can you tell me a bit more why the Perl commmunity does not use PerlUnit?

PerlUnit seems to be have been abandoned. To put that to the proof, you might like to ask your question on the PerlUnit mailing list and see what sort of response you get.

OTOH, the author of Test::Class is an active member of the Perl qa community, fixes bugs quickly and makes regular releases. Test::Class is more Perlish, works with other Test::Builder based modules and has excellent community support. This is all discussed in the Test::Class documentation.

As for why PerlUnit never seemed to gain traction in the Perl community, that is an interesting question. My guess is that it is mainly cultural: Perl has a long tradition of testing and qa, it worked well, folks were keen to further improve it and saw no reason to switch to an xUnit-based framework. Perl has a thriving qa community and continues to hold well-attended Perl QA hackathons. Also, Perl is a multi-paradigm language (in constrast to OO-only Java where JUnit rules). Notice that multi-paradigm C++ has similarly not embraced an xUnit framework the way Java and C# (NUnit) have.