The duty to vote in Belgium belongs to all adult Belgians. EU citizens can vote in European and municipal elections. Other foreigners have local voting rights when they have lived in the country for more than five years. Attendance is compulsory for Belgians in Belgium, not doing so results in a fine, 3 fines equals the loss of civil rights.

It can be done, but I was also part of an election oversight or whatever committee, we counted votes and stuff. One of the things we did was we took a vote urn to the local retirement home and well I witnessed what happened when voting is mandatory. In the past It was mandatory in our country as it was part of the eastern bloc and this man just took the first paper, not even reading which party he voted for and just put it in the envelope and voted that way.

So there are definitely downsides to trying to encourage voting too.