As far as I can gather from various anglo expat-pages lists of eligible voters are kept by local government. This might mean trouble for voters who become homeless.

SPAIN: Madrid Mayor Wants to Sweep Homeless Out of Sight - IPS ipsnews.net

Everyone on both sides of the argument is aware that the vast majority of the people sleeping rough and enduring the cold at nights are unemployed and homeless as a result of the prolonged global economic crisis. They are immigrants from Latin America, Africa and Eastern Europe, as well as large numbers of Spaniards.

So your snark might hold a bit a truth, austerity might have removed those voters from the rolls.

A vote for PES is a vote for EPP! A vote for EPP is a vote for PES! Support the coalition, vote EPP-PES in 2009!

There is rounding errors; the new basque left independentist party got 330 thousand votes and 7 seats, but I didn't list it because it got under 1M and didn't contest the last election; the new green left party got 230 thousand votes and no seats; and then there are a bunch of minor parties. Also, roughly 1M votes are registered while resident abroad and their votes may not have been counted, though estimates are that less than 1/3 actually voted.

To err is of course human. But to mess things up spectacularly, we need an elite — Yanis Varoufakis