Has it really or have your expectation increased instead? Or is it because they initially only worked well with business us english and have been trained over the years to support many more languages, dialects and even variations of said dialets/language + slang and profanity?

Also at the beginning people where talking to these slowly, articulating every word. Now everybody take it for granted they should be understood and talk in their lazier and more natural way.

I've never activated speech recognition on any device I own. But last week I was in a videocall with my partner's mexican family and early in the call they were trying to make my mother in law's Amazon Echo to stop the music and it only really stopped when my sister in law started using profanity words, something like "no mames! chinga to pinche madre Alexa cayate!"

Apparently this stuff became so used/trained by people not using them in a polite way that they eventually only react when you talk badly to them using slang and profanity.