Samsung phones come with a security seal that says you should not buy the phone if it is broken. Is this proof that no one has tampered with the phone?
Is there some way to take off the seal and paste a new one. Perhaps with special tools?
Someone, could also just take the phone out, do whatever he wants with it and then using some machines create a new box and seal, right? What do you think the possibility of this happening is? I don't think this would be hard to do.
No. They exist primarily to make you comfortable with your purchase.
As Steve noted in his comment, most anti-tamper seals are actually easy to tamper with. The attacker just needs to dedicate some time to defeating that particular make/model of seal.
This is similar to standard door locks, which you probably have on your house. Any decent locksmith or a well-equipped thief can compromise a standard lock in a matter of moments. Depending on where you live, there are likely dozens (if not hundreds or thousands) of people who could walk into your house on a whim.
The seals may have a deterrent effect on casual handling, but they are completely ineffective as a security measure. There are some anti-tamper products that are truly difficult to defeat, but no one is spending that kind of cash to "protect" consumer products.
This would be disparaged as security theater if anyone seriously claimed it offered some measure of protection.
