The existing link is a correlation, not necessarily causality.
For example, imagine a country where the government can (and once in a while does) decide to take away your savings. In such country it wouldn’t make sense to try getting more money than you need to survive this month, unless you are ready to use it now (e.g. you are building a house). Imagine that you are smart enough and you could make more money than you need, but the money would probably be taken away, so you don’t want to do this. So instead of higher salary you will optimize e.g. for less work. If enough people do this, work ethics goes down.
Or imagine a country with such strong egalitarian ethics, than even if you do 10× more work than your colleagues, your employer just wouldn’t give you even 2× higher salary, because in their opinion, no one deserves twice as much as the market rate. Again, the usual response is to slow down to the level of average (sometimes even more, because the average people usually consider themselves to be above-average, so they slow down too).
There are countries where stronger work ethics would be a lost purpose; it would not improve the life of the given individual, on average. Sure, some people are strategic enough to find a way to do it, but most people are not. (For example, if you are 8× faster than your colleagues, but your employer insists on paying you exactly the same amount of money, you could try convincing them to let you work from home, then do in 1 hour what your colleagues would do in 8 hours, and spend the rest of the time working on your own projects or just having fun.)
The existing link is a correlation, not necessarily causality.
For example, imagine a country where the government can (and once in a while does) decide to take away your savings. In such country it wouldn’t make sense to try getting more money than you need to survive this month, unless you are ready to use it now (e.g. you are building a house). Imagine that you are smart enough and you could make more money than you need, but the money would probably be taken away, so you don’t want to do this. So instead of higher salary you will optimize e.g. for less work. If enough people do this, work ethics goes down.
Or imagine a country with such strong egalitarian ethics, than even if you do 10× more work than your colleagues, your employer just wouldn’t give you even 2× higher salary, because in their opinion, no one deserves twice as much as the market rate. Again, the usual response is to slow down to the level of average (sometimes even more, because the average people usually consider themselves to be above-average, so they slow down too).
There are countries where stronger work ethics would be a lost purpose; it would not improve the life of the given individual, on average. Sure, some people are strategic enough to find a way to do it, but most people are not. (For example, if you are 8× faster than your colleagues, but your employer insists on paying you exactly the same amount of money, you could try convincing them to let you work from home, then do in 1 hour what your colleagues would do in 8 hours, and spend the rest of the time working on your own projects or just having fun.)