If it's at all difficult just reply saying something with the 'GDPR' keyword and they'll hop on it.

A few times I've had unsubscribe links absent or not working for whatever reason and done that and a human's replied and sorted it out.

I was recently subscribed to ~500 newsletters within 10 minutes, and the most annoying ones to unsubscribe where from Brasil, US, India, etc.

(An attacker used the paypal guest account feature and used my IBAN [european bank account number] and tried to hide the mail within those hundreds of mails. They were successful for some days, until the purchase showed up on my bank account)

What do you mean, how is there a difference between unsubscribing a newsletter from a EU company than a US company?

This is my experience as well. US emails are one-click unsubscribe almost without fail, while EU and AU especially require multiple clicks and often entering my email address to unsub. Extremely annoying.