The screwfix website really wants my mobile number when I place an order: phone number is a required field on the order page, and SMS is the only way to receive notification when the order is ready for collection.
Why do Screfix want my mobile number so badly? They send me an order confirmation email, so why can't they send me another email when the order is ready for collection? Surely most people can receive emails on their phone nowadays.
Toolstation use email, so it's not like it can't be done that way.