Kia entered the 'western' market by basically selling the cheapest new cars you could buy. While this bought them much needed market share, it also gave them a reputation for being cheap, crappy and unreliable. While 'modern' Kia has moved beyond this, and as you say, the EV6 is been getting pretty great reviews, the memory of those days of cheap unreliable cars still linger.

When they became popular in America in the late 90s and early 00s they were the absolute lowest price cars on the road and had a corresponding reputation for quality/reliability. They were what you bought if you wanted to buy new, but couldn't afford to pay for Japanese reliability. Friends that bought them new had major mechanical problems within a few years. Their gutter reputation is what led them to offer the 7 year warranty, to try to signal quality and reassure people that the problems they would inevitably experience would be fixed by the company. I'm sure they've gotten far better than then, but they're still nowhere close to Toyota/Honda in reputation. When there exist manufacturers that have been building cars that are reliable for decades, for decades, for only a few thousand dollars more, I am loath to consider buying from anyone else.