Why does English omit diacritics from foreign names that still use the Latin alphabet? For example, why are the Czech tennis player Tomáš Berdych, the Norwegian crime writer Jo Nesbø or the Polish city of Łódź so often simply spelled as Tomas Berdych, Jo Nesbo and Lodz?<br>
Within their native languages these are often separate letters, and in The Netherlands they would always use these diacritics where possible. So what's the reason that English often omits these?

Two examples:<br>
http://www.bbc.co.uk/sport/0/tennis/31042458<br>
http://www.amazon.co.uk/Jo-Nesbo/e/B004MSFDCG/ref=ntt_athr_dp_pel_1

(Note: I am only talking about names using the Latin alphabet, I am not talking about transliterated names)