Finnish cops are obsessive over fighting cannabis, and in practice even having a single joint on you will lead to a criminal record, and not for just "personal use" or "possession" but the same crime you'd be charged with if you grow 27 plants at home.
And yes, I've personal experience on both, as well as several dozens of other examples, documented and otherwise.
Finnish drug laws are just as archaic as others, and the cops attitude and understanding is way worse than in most European countries.
It's ridiculous.
So yeah, Finland is definitely wrong, fucking hell.
It's like the "happiest country on Earth" bullshit.
Yes, Wikipedia is right that technically there is a way for police to not enforce the law when it comes to personal amounts of cannabis, but in practice that never happens, and the cops make even the smallest bit of weed be a "proper" drug crime. Medical use is technically legal, yeah, but there's like at most a dozen people in the country, and most doctors would never ever even consider cannabis to be medicine, and even tiny use admitted to a doctor might lead to a loooot of discriminatory bullshit.
Basically the education material for the police and the doctors seems to have been "reefer madness".
Just google "police prevented filming" in Finnish, "poliisi esti kuvaaamisen", and see how many articles come up where you're not allowed to even film protests or even when the police conduct a search at your home, you're not allowed to film that, according to the police.
That's an article from when the police illegally searched my apartment and prevented me from filming them by grabbing my phone away from me. The supreme court decided they were wrong. But for 90% of the things they did wrong that day, the grabbing of my phone was the only thing I got them on, because I still had the clip of them actually grabbing the phone.
Finnish cops are undereducated authoritarians. Good in comparison to other countries police in a lot of things, but still not something to be desired when it comes to cannabis and matters of personal rights.
So even though I know the map is wrong, Wikipedia wouldn't allow me to change it because on paper there's a reference to a possibility of not being charged for personal use, even though that never gets utilised in practice.
Ofc they wouldn't be, because of the variation within people.
But the study and especially the way it's reported is complete and utter bullshit. The study itself looks at contentedness, not happiness. That's very different, and when the Finnish cultural context is added, the difference is exacerbated even further.
I'm not saying Finland doesn't have good social programs compared to other countries, but that doesn't mean they are good social programs or that they don't have massive systemic issues of their own.
So yeah, I can easily believe that according to subjective reports, we are the most contented country, as we have functional programs to keep everyone housed and fed at least, and it's not in the Finnish culture to complain. So you'd go "no ei voi valittaa" = "well, I can't complain", meaning "it could be worse" or "I'm alright", whatever your preferred form might be, which easily translates to "I'm content enough" which translates to a study showing "the happiest country on Earth".
It's much the same thing as when you see headlines saying "a glass of wine is equal to an hour in the gym" or "chocolate cures cancer" or something like that. It's very misleading reporting.
Wikipedia operates in a very specific way. You'll need a web article that says what you're trying to tell them. They don't accept first person accounts. For similar kinds of things in the US good places to look would be, NPR, Pro Publica, or the ACLU. If you have groups like that in your country then check them out.