I heard from an Irish colleague (I'm a Brazilian expat in Dublin) that this attitude, in particular towards taxes, changed after the independence from the UK.
So yes and no. My parents are pretty old (they had kids late) and they really don't like telling revenue (the taxman) anything, and would be inclined to overlook tax avoidance and whatnot. My wife's parents are of a similar age, and also similar on this.
Now, all of them were born a generation after independence, so it's definitely not just that.
However, when the government has historically not given a crap about you (as the British government did not), it leads to a disconnect from the society and institutions that increases the probability that you'll be OK with tax dodging and not have as much trust in the overall society (because historically, it didn't care about you).
So, I'd say that it's slowly changing because we're not a colony anymore, but it definitely didn't just disappear in a puff of smoke in 1921.
Now, all of them were born a generation after independence, so it's definitely not just that.
However, when the government has historically not given a crap about you (as the British government did not), it leads to a disconnect from the society and institutions that increases the probability that you'll be OK with tax dodging and not have as much trust in the overall society (because historically, it didn't care about you).
So, I'd say that it's slowly changing because we're not a colony anymore, but it definitely didn't just disappear in a puff of smoke in 1921.