I have often thought about this issue, especially when waiting for my wife to finally join me, but I can see why it happens.

I think marriage has often been abused for economic gain.
There have been so many false marriages in the past to get people into the UK, and other "wealthy" countries with respect to third world countries.

Prostitution is caused by women not having enough money, and if checks are not done there would be hundreds of thousands of women entering the UK to make money for organised crime organisations.

Sadly for us, waiting is one of the pitfalls of marrying a lady from the Philippines.

I just don't understand why it costs us £500+ to get our documents checked.

(Hi badgrimly, just a suggestion: please break your paragraph into sentences....much easier to read......Thanks)