Do Machine Learning and Vision Labs outside the USA hire non-student,non-postdoc Research Assistants?
Short answer to the question "is it possible?": yes, it is. E.g. in Germany, we can employ a person having some academic degree. The more important question is: What would you be willing to earn because at least in Germany, academic position usually are not the best paid ones.

If you just want to earn money and get experience, I would recommend a job in industry. If you really want to learn and develop yourself, and you don't have to earn much, look around in Europe. If you bring your own money (e.g. DAAD scholarship), you could start in my lab ;o).