There is no valid reason, moral or technical, for preventing voters from verifying their votes were accurately counted, and verification does not enable any new crimes – but it does prevent the current crime where someone's vote is either miscounted or not counted at all.
Personally, I would like to have a receipt because I think the danger of my vote not having been recorded is greater than the danger of someone demanding my vote receipt off me.
Sure they do: use a lie detector and ask them.
Honestly, the situation you describe is the problem, not the presence or absence of verifiable voting. If you've got the mafia threatening your family, voting is the least of your problems.