Fred says:

It is a game. I remember asking a manager of my local Sainsbury’s why, during the infamous Mrs Curry salmonella egg debacle a good few years back now, why health warnings were not displayed at the time – “oh everyone will forget it all by next week” was the whispered response.

Lots of eggs have traces of salmonella, wherever they come from. Just be sure to cook them really well!

And Frank, “how do you know if anything is wrong with them”. You find that out very quickly after eating some.

M.L. Finlay says:

Cheap Spanish eggs are eggs that come from factory farms – where they trim their wings, cut their beaks, force them to lay more eggs by starving them and stuff them into small cages with 10 other birds. Foul conditions would be a gross understatement.¨Cheap¨ because it´s the cheapest way for the farmer, but at what cost to the environment, the animals, and ultimately us? There are 4 kinds of chicken eggs sold in Spain, each with its own code, the first number being the most important. 3 is what we just talked about, and 2 isn´t much better – no cages but thousands of chicken squeezed together on the ground with no room to move and many dying just from heat exhaustion or the very high content of ammonia in the air. The packaging will have enticing words such as ´fresh´ and the price will be great. AVOID THESE AT ALL COSTS!!
1 is ´huevos camperos´, eggs from free-range chicken. No cages, free to roam outside with a mostly grain-fed diet. These can be bought in most supermarkets like Eroski, Supersol, or Carrefour (Mercadona does not sell them however, at least to my knowledge) The best eggs have a code that starts with 0. These are from free-range chicken given organically grown feed, with no antibiotics or growth hormones. A little tougher to find, but your neighbourhood organic shop will surely carry some.
What we buy is what we encourage.