I went with my uncle recently to get him a new phone. His had worn after years of heavy use, and he was due for an upgrade. We went to a store operated by his cell carrier. After selecting his new handset, my uncle asked the representative to transfer his contacts from his old phone.
The representative, using a piece of machinery not unlike a point-of-sale credit card terminal, connected both phones to transfer contacts. Before he began the process, the representative advanced through several of the setup screens on my uncle's new phone. This involved agreeing to several license agreements. The representative did what many computer users have trained themselves to do - he advanced through each agreement, dutifully agreeing without reading the contract.
He was agreeing on behalf of my uncle without permission to do so.
This must be happening hundreds of times every day. Imagine all the phones, computers, tablets and other products being set up by helpful sales associates all the time.
I noticed this due to my familiarity with license agreements. I took a course which heavily focused on them several semesters ago. A less technical user, however, wouldn't know the difference. They wouldn't realize an agreement had been signed.
I've purchased technology where the sales representative asks me to sign an agreement electronically. This makes much more sense. Unfortunately, as shown by my anecdote, this policy is not universal.