Many of the EE girls work in groups, or at the very least in pairs, and wouldn't you want the safety and company of another person when working in a foreign country. Many of them also work in managed groups with the convenience of having someone else arrange the accommodation, advertising and bookings. Most take frequent breaks back home.
There are some fantastic girls, many just here to fulfil short term goals such as paying for college, saving to start a business or buying property back home.
In Birmingham there is good Czech group, including Amanda.29, working out of a flat near Moor St and the Hungarian Divas group, including Paris Lamour, just off Broad St at the Fiveways end. There are sure to be others, these are just the ones that I have used. I don't know of a Polish group (this doesn't mean there isn't one) but have punted recently with Michelle Independent and Emily@19, both top notch Polish girls, and there is also Pola who is very highly regarded (I have yet to see her).
This is not to say that there are not some good English girls around too, but you asked specifically about EE girls and I have only mentioned the ones I have seen (with the exception of Pola). I have two fantastic regs out of the region, one Hungarian and the other Bulgarian. As has been mentioned , Romanians are probably best avoided unless well reviewed here on UKP, they are generally unenthusiastic, offer limited services and are often mediocre at best, but there will be some exceptions. Plenty of good Czechs, Hungarians and Poles though and most are not to be feared, in fact I'm convinced that the punting scene in the UK is all the more richer and affordable due to their presence.