One of the things most English people find shocking when they go to Spain on holidays is that we don't say "thank you" "sorry" for every single thing we do to others or any sort of minimal human contact. I know English might find this irritating and interpret it straightforwardly as a lack of politeness.

Does this make Spanish less polite? Spanish have their own conception on how to behave politely, which does not necessarily have ot be the same as the English. For Spaniards, it is not necessary to say thank you for everything, it depends on the intonation, on how you say it rather than what you say. If you go to a typical bar in Spain and order a beer you can say thank you but if you don't it won't necessarily be intrpreted as disrespectful, it will depend on your attitude, your smile or your friendliness in dealing with the waiter rahter than saying exclusively "thank you". Many times "thank you" is not used becuase it is implied in the exhange, in the look, in your behaviour.

But If you say thank you too often in Spain for very simple exchanges (when it is clearly not necessary) you may make people feel puzzled or suspicious. That's the difference with the English culture where "thank you" is a conventional answer to almost any kind of acitvity, even if it is not necessary.

Remember, Spaniards are not less polite just for having a different understanding of what politeness is!