Domain name differences

Just doing some analysis on keyword phrases that are targeted at one particular country. The URL though is from another country. Google seems to really penalise this senario, i.e. for example a .de extension optimising for keyword phrase with uk in it. I am seeing that you can rank highly in Google.com but for say Google.co.uk, unless you have a .com or .co.uk (or .gov) you can forget about a high ranking.