So what you are basically saying is... whatever the UK Government does with regards to Border Control... in order to minimalise Illegal Immigration... is essentially pointless?
Yes. Border control is a totally dead concept in modern Europe.
You need to realise that the "Daily Mail headline" entry techniques (50 Vietnamese packed in some container) account for virtually nothing. The other 99% come in overtly, with legal paperwork.
If you don't like it, campaign for the UK to withdraw from the EU.