I'd say English listeners are incredibly fault-tolerant because of how diverse English speakers are. Languages with fewer, more localized speakers are less tolerant of poor pronunciation because there's less variety in what they hear.
This x 100! My pronunciation in Czech is now pretty bang on, but when I started I didn't elongate "long" vowels enough - by that I mean a vowel like "á" should be pronounced about 50% longer than "a". My great example is when I was trying to tell my friend something about a pub called "u čápa". She told me she didn't know it, which was surprising as it was well known within my friend group. I explained its location and she said "ahhhhh, you mean u čápa!". I couldn't believe it - the difference between "I know this" and "What are you talking about, I have no clue what that could possibly be" was like 50 milliseconds more "a". But it makes sense - if you've only ever heard correct Czech your likely won't know dodgy Czech. Most native-English speakers have plenty of exposure to various levels of English-language ability, either directly via speaking to a tourist or indirectly through various other media (radio, TV, film, podcast, music).
