Maybe it was different being in a residential area rather than on a tourist complex but I would say, Catholic or not, the tradition was there in my part of PDC.
'The tradition' is in America, not the UK nor Spain. Some suggest that it is almost devil worship. They are certainly a pest round here.This trick or treating is great till you ask them for the treat !
The Spanish don't even celebrate Christmas either but the sixth of January, to celebrate the magi who visited Jesus.
We wouldn't send our kids knocking on strangers doors anyway. Keep your little one's safe.
p.s. When we were in CT last December, there were pics of a little spanish lad who had disappeared, all over the place. He was about 8 years old and wore glasses.
His pic was alongside the little girls pic from the UK who had been kidnapped in the Algarve.
Did they find the little lad ?