My utility company used to include the bill amount in their email which I used to pay using my banking app. But no, where is the fun in that! So they built an app, because what is the utility of a utility company without an app, removed the amount from the email so that I can give my fingertips some much needed workout and open the cursed app just to see the amount. I think the app has a feature to pay as well but being the minor lord of pettiness that I am, I refuse to use that and still pay using my trusty banking app.

They do that to match your device ID or cookies with their customer records. Since cookies don't last long they prefer to have you do that every month.

More details here: https://hightouch.com/blog/what-is-identity-resolution