This is definitely the case here in Spain. I've been to the voting centers a few times and they have tables outside the voting rooms with piles of voting slips similar to[0]. You see families come in and the younger members have no ability to secretly vote for whom they desire as the slip you pick is for a party and you are selecting that in front of anyone else that is there.

Being from the UK where we mark who we are voting for in a private booth, on a slip with all candidates [1] fold the paper in half so no one can see and post that into a box, the Spanish system makes me uncomfortable. Let alone that people mess with the stacks of slips, hiding smaller party's slips under other piles…

[0] https://c8.alamy.com/comp/KN3EHD/a-hand-pick-a-voting-paper-... [1] https://www.unlockthelaw.co.uk/images/Ballot_Papers_General_...