What More Could Companies Do in Order to Avoid This?

I recently caught a 69-year-old acquaintance setting up a new Hotmail account. I knew he had one from a long time ago so I asked him why he needed a new one.

"I need to create an account in order to fill out this survey. It says here 'Please enter your email address. This email address will not be used for any purpose other than administration of your account.'"

"How many times have you created a new email address specifically to create an account?"

"Well this account is johnsmith26, so 26 times. I can never remember which account is for which service!"

I explained to him that "This email address will not be used for any purpose other than..." was from the company's point of view (ie privacy-related), and not a command, and we had a chuckle about it but it got me wondering, how much more could the company have done in order to avoid this situation? And not just this company - 25 other companies haven't made it clear enough that your existing email address will do. Similar anecdotes are also of course welcome.