Is the World That Big?

I hate doing the bills. It's so tedious and boring, not to mention depressing. I'm pretty dubious about writing the account number of the bill on the check--'cuz you just never know what 17 year old they've got working that area and I'd hate to have the lights shut off due to clerical error. My complaint today is just something that makes the process even more tedious:

Our account number for our cable has 13 digits. 1,000,000,000,000 That's how many numbers it is. I don't even know what that number is.

The account of our natural gas has a whopping--count 'em--sixteen digits in it. 1,000,000,000,000,000 Can anyone tell me what number that is? I don't think even the national deficit is that big. Oh, give it a couple years...

My point is that I would think there should only be as many number in the account number as there are people in the world. Otherwise you just don't need that many numbers.

Here's something funny: The account number for our phone bill starts off with our personal home phone number, area code included--then they add another five digits afterward.
What gives? Does anyone else in the world have the same phone number as me?

Even our cars only have six digits...