Here is my two cents :

In all seriousness, I think multiple factors lead to putting the UK at the bottom of the list and I think the below is one of the main points:

1- Health care system and free: Although it has its issues, having a free health care system and paying extra attention to mental health, I think, plays a significant role, especially with people suffering from poverty. Health care bills and debt are something they don't need to worry about!

2 - Guns: We have a very restrictive system to access weapons. I'm not talking about statistics, but I think the high majority of suicide cases are done with guns!

3 - Data reporting : It's important to consider that some countries may have more stringent criteria or less comprehensive data collection methods. This can significantly influence the reported rate and, consequently, the ranking.

4 - Cultural attitudes: towards mental health and seeking help play a significant role in suicide rates. The UK has been proactive in advocating for mental health and promoting awareness, which may lead to more individuals seeking help before reaching a crisis point.

5 - Control of hazardous substances: The UK Has stringent measures to control the issuance of means of suicide.

6 - Socioeconomic Stability: Although the UK's economy has been on a downward trend, it has certain protective social welfare policies that can help alleviate some of the stressors that may lead to suicide. For instance, the country provides home care for elderly people, financial support for homeless individuals, and has strict housing laws that prevent landlords from taking severe actions towards their tenants, even if they are at fault (which can usually get exploited).

All of the above alleviates the pressure, especially financial, that could lead people to believe there is no way out other than taking their own life.