At least for the leisure business, there have been a development of "scandinavian" language, sometimes referred to as svorsk (swedish-norwegian). Before Thailand was "discovered", Greece and Spain were the major destinations for sun seeking scandinavians, and the leisure companies usually could fill entire hotel complexes with scandinavians. So, airline staff and guides needed a way to speak to everyone. 'Svorsk' avoids difficult words, and softens the pronunciation to a middle-way between the three.

I'd say I heard the practise of svorsk a few times on SK too, but especially when the crew is danish or norwegian and the O/D is sweden.

As other said, no. People living in border areas are those who usually have a good bi-langual understanding. And in general, few people are good bi-lingual speakers. The reason is that the languages are too similar, which actually makes pronunciation more difficult.