Is it because of national security or something else?

A bit of rant... with a desire to understand what's actually happening...

From the reviews I've seen on Chinese EVs, they're super cool and seemingly more affordable. But they're not sold here in the US. Google tells me that it's because of security concerns - i.e. over the air updates that could stop the cars from working or they could secretly be listening on our conversations. 

But what I don't get is that Volvo, although a Swedish brand, is now owned by a Chinese conglomerate (since 2010). You can buy a Volvo so easily here in the States. Why are there no concerns about national security? And Chinese EVs can be purchased in the UK. Are they not concerned about security?

What's actually at play here?