These are just my thoughts on this system:
Well have you ever had to return something and can't find that receipts, and they say sorry you can't return with out the receipts...or that cool power head crapped out 8 months into its life and now you want to exchange it...and you through away the bill. Now this is stored in the computer, under your name.
or
Hey its year end and lets give out gift certificate's for everyone who spent $$$ at our store this year.
or
There is a major recall on X brand pumps. they get the recall notice and then they can check there data base and call who ever bought this pump to let them know about it.
There is another LFS store here that does the same thing if you want to collect points as well...but they use a Card insted.
I visited another LFS in Burneby and if I gave them my name and address they could knock off the PST because the supplies were going out of province.
Your name and phone number, is in general, public knowledge....its in the phone book

unless you have a unlisted number.
We have a similar system in our shop , we can't give a final price on a job without a PO# and customer information.