Why? Because this allows you to appear to be cooperating with any request to look at your computer. Simply type in the level 1 stuff and demonstrate the system booting up. I bet 9 times out of 10 whoever is checking you over will stop right there: it looks a lot like compliance. If they keep pushing for total access to your data simply say "no" Whereas if you say "no" to begin with, you're likely to attract more attention than if it appears you have nothing to hide. In many cases people are working jobs where they only have so much time to check things -- unless there appears to a be a person with a problem, in which case they can take all day with you. So help them out. Give them something to ask you for that you can produce. Then everybody can move along and it's not a problem for anybody.