When someone thanks you, you would probably reply them with a “you’re welcome” or “no problem” – it’s just common courtesy. However, you’ll find that older people tend to say “you’re welcome”, while younger tend to say “no problem”. While we can put this down to the “changing of times” or simply a new slang, there’s something a little more nuanced.
As a general consensus, it’s more polite to use “you’re welcome” because that’s what’s normally taught at school. However, you almost never hear a younger person say “you’re welcome.”
For older people, the act of helping or assisting someone is seen as a task that is not expected of them, but is them doing extra, so “you’re welcome” is saying “I accept your thanks because I know I deserve it.” It could be construed as an acknowledgement by the thanked party that they did do something worth thanking.
However, in an extreme case, this could be construed as more selfish or even arrogant, because the thanked party is allowing attention to be on them, instead of the other party. For example:
“You’re welcome to this open door, which I am holding open.”
Another reason most older people prefer “you’re welcome” is because they feel it’s a privilege they deserve – especially in a setting where they’re a customer (ie. thanking a staff after receiving a cup of coffee).
For millennials and younger, “you’re welcome” is sometimes used sarcastically when they haven’t been thanked – and it’s a phrase that’s used to point out someone else’s rudeness.
“No problem” is used mostly by younger people, because they feel not only that helping or assisting someone is a given and expected, but also that it should be stressed that your need for help was no burden to them (even if it was). It can be construed as an act of humility or deference.
“It was no problem for me to hold the door for you, because your ease of access is more important than me getting to my destination faster.”
From an older person’s perspective, however, saying “no problem” means that whatever they’re thanking someone for was in fact a problem, but the other person did it anyway as a personal favour.
Compare this with “nou’re welcome”, which could be construed as an acknowledgement by the thanked party that they did do something worth thanking.
Obviously both connotations are usually very minor and mostly ignored. The reason for these preferences is down to older people thinking help is a gift you give, while younger people think help is an expectation required of them.
Of course, you can use other types of responses closer to “you’re welcome” which include “no worries”, “my pleasure”, or “don’t mention it” – these often vary by geographic location and culture.
However, these implications may explain why “No problem” has become more common, and could even be seen as a more polite reply these days.