Under copyright law you don't need their permission to use the software, anymore than you need Stephen King's permission to read one of his books. To use software you need a computer and a legally obtained copy of the software. Copyright law takes care of the rest (by giving you the right to execute the software on a computer and even make modifications for the limited purpose of getting it to execute on the computer).
This is all true. However, the catch is in the "legally obtained copy" part.
Without agreeing to the license, you haven't legally obtained ownership of a copy.
if the copy was made by someone authorized to make the copy (for instance the copyright holder), and someone authorized by to sell the copy sold you the copy (for instance an authorized distributor) then the copy is an authorized copy - i.e. "legally obtained copy" to re-use the phrase we both agree on. There is no additional requirement in copyright law beyond possession of the authorized copy to execute software on the computer even though the computer makes its own internal copies as a result of execution.
At least - this is explicit in Canadian Copyright Law. I'm not going to argue about US law.
So in Canadian law, unless you agreed to some kind of restriction in connection to that act of Distribution then once the distribution is concluded you may rely on the full extent of copyright law and execute it on your computer. You can tear up that EULA because you don't NEED a license. You have the law.
your analogy of a ticket is invalid. You can be denied entry to the venue in accordance with terms because those terms are terms for entry into the venue. A venue which does not belong to you.
On the other hand, your copy DOES belong to you. so nobody can impose additional terms without your consent.
it would be more like if you buy a hair drier for $20 from an authorized distributor: Then it arrives at your house with a sticker on the "on" button, saying that "you must agree to the following EULA in exchange for the license to use the hair drier. pressing the ON button on the hair drier indicates that you agree."
Since you don't need permission to press the "on" button on your own property, you can freely ignore the sticker and use the hair drier. Further more since pressing the ON button does not communicate anything to anybody except yourself, it can't be said to signify an agreement. agreements require a meeting of the minds.
having sold you the hair drier, they can't hold YOUR "on" button hostage in order to compel you to agree to their additional terms.
This may almost all be moot as software has largely moved beyond consisting of merely a physical copy, but often now depends on access to online services. Access which in fact DOES require permission to access somebody elses computer system.
