European immigration systems are still being implemented IT wise. Most of the times they use some electronic device that records your passport and the system is supposed to record
your exit with no stamp. The entry stamp is for the benefit of authorities that do not have access to the system but may want to check you out during your stay (e.g. police in the city). The real problem is when they let you out of the Shengen area without a record
in the IT system. Then (as I mentioned in a previous post) when you return to the Shengen area they get confused to say the least.
This is my actual experience...