Why does Verizon have 2 different logins for Wireless and Residential?

[#1]

I have been a Wireless customer for years. Today I signed up for Residential services and after I had completed my order I found out I have to create an entirely new account and sign-in for my new Residential account. Part of the reason I signed up for bundled services was so I could handle everything under one single streamlined account. It seems ridiculous that Verizon doesn't let you have one single login. I called customer service and they said sometimes Verizon offers this option and sometimes they don't and that it's up to the whim of their marketing deparment. Anyone else have this complaint? 

[#2]

Because they are different companies although under the broader Verizon name.

[#3]

Verizon Wireless is an entirely separate divison from the side of the company which supports FIOS/consumer markets.  So they have different login's.