Unfortunately however, there are a lot of grey areas... To name a few:
* Amazon have been in a long dispute with the Brazilian government, over the right to operate a .amazon TLD - as the Brazilians claim it should instead be related to the rainforest.
* On the other hand, Amazon have secured TLDs such as .prime, which could also be disputed. Apple have won .apple, Sky have won .sky, ... the list goes on.
* Sometimes, the conflicts can even be with foreign languages. For example, Ferrero are now the registry operator for .kinder - but as this is the German word for "children", it's been the cause for similar debate.
Also, with regards to your concern that there is a lack of variety in available unrestricted TLDs - I disagree; if anything, there are far too many (there's hundreds!!).