They state that there is no word for please, then go on to say that you can add tack/takk/tak for the same effect. Make up your mind, tack

I mean you just express it a different way. Only about 20-30% of langauges have the word "have". In english you say "He has a book" while in hungarian you would say "He has a book at him". This doesnt mean people dont possess stuff in hungary and im not gonna write a clickbait article about how hungary is a radical post-marxist collectivist country where people dont even understand possession. Okay, i mightve went over the top but you get it.

Norwegian has 'x, vær så snill' which is functionally 'x, please' so far as I can tell. Adding 'takk' (thanks) at the end of a sentence is another way.

Doesn't Swedish have "snälla" which serves the purpose of please pretty well?

Thinking of this later, isn't our English usage of 'please' contracted from 'if it pleases you' as in French "s'il vous plaît'? This would be closer to the Norwegian 'vær så snill' I mentioned in a previous post, I think? Looking at one source on old English, though, shows 'Iċ þancie þē' which looks like 'I thank thee' to me. It's interesting.

At least in Finnish there are ways to communicate politeness without a separate "please" -word. For example, "Can I have..." (="saisinko...") is already considered polite enough.

In Scandinavian languages the same reason there's no word for "please" in French, Dutch or Spanish.

Because having a short verb phrase does the trick just fine, there's no need for a single word to develop.

And in Finnish because in Finland thanking is much more important than in Indo-European cultures and Finnish has built its equivalent of the word "please" directly into grammar.

We have several phrases that are used in different contexts in Danish, but no universal "please". I'm sure it is the same for other languages.

Dictionaries may be wrong but there are example sentences of their words for please:

https://en.wiktionary.org/wiki/vennligst https://en.wiktionary.org/wiki/sn%C3%A4lla#Swedish

"I've never heard of anyone sending a physical thank you card after a job interview or something similar," she said

Is that a thing? I've never heard of that neither.

True, apart from "ursäkta mig" there is nothing in swedish. You can thank people in advance