Hello!
Own reg in these (and other countries) (ie F in France etc.)
German reg. in Germany: Cost sharing is (still) legal. As long as the aeroplane has 4 seats or less, no permission is required. The costs can be shared among the passenger(s) completely, the pilot does not have to pay his share. But he is not allowed any kind of remuneration, wether he has a PPL or CPL does not matter. Above four seats, permission from the local aviation authority is required (not from the LBA! ("our" CAA)). Usually, this will not be granted.
However, a permission for "non commercial transport against payment" (Nichtgewerblicher Transport gegen Entgelt) may be issued instead. With this kind of permission (issued by the local authority) a certain number of flights with full coverage of expenses - even remuneration for the crew! - is permitted. There are strict rules to be obeyed, the most important of which is that these flights must not be advertised or publicly sold in any way. Usually, this kind of flying takes place when a company aircraft is chartered out to another company together with crew and everything. I have done quite a lot of this kind of flying in the past!
All this has nothing to do with JAR-OPS / EU-OPS which only regulate purely commercial flying. This may change in the near future, as rumour has it...
Greetings, Max