For a variety of reasons, people change their email addresses much more often then they change their home address. Sometimes emails will get forwarded to the new address, but usually not. First class postal mail normally is forwarded for one year.
To provide some background, around the time that was instituted, circa1970, despite automation the pre-divesture Bell System had more operators than in manual days and the labor costs were high. Information services represented a huge proportion of that cost. They realized a great many people were using Information for numbers already in the phone book, and some callers were making very heavy use of it. Also, as a result of competition the Bell System began to change its rate schedule from 'average' to 'usage'. Low cost users would pay less. MCI didn't offer directory assistance and it was foolish for the Bell System to offer that as a free service to a competitor.
Fast forwarding to today, I just saw a big Verizon poster ad for 411 information services; they provide a variety of information now. I don't believe the price was mentioned on the ad.***** Moderator's Note *****
"DA" services were often used by bill collectors and other high-volume call originators, who were externalizing the cost of locating their targets when those they were chasing changed addresses or phone numbers. Research also showed that the highest volume non-commercial users were young customers who had never bothered to write down a number, so some "throttling" of the service was justifiable.
I do, however, feel strongly that non-commercial users should have a few calls "free" each month. Such allowances increase the likelihood of new business calls, make it easier to get help after a tragedy, and benefit the elderly and infirm, who may not be able to write anymore.
Bill Horne Moderator