What you are stating is that the user MUST waste time and money entering in 4 differernt URLs (wasting users money and time) for them to access a website via mobile. Yes, it would be great IF ALL companies use one URL standard accessing mobile websites.

Let's use Twitter, which is a common website that most people use. You have a mobile phone. You want to access the mobile website. Choose the URL:

http://www.twitter.com/m
http://www.twitter.com/mobile
http://m.twitter.com
http://mobile.twitter.com

OR just enter one:
http://www.twitter.mobi

Surely a company could use php to redirect mobile devices to the mobile site, but NOT ALL companies have such employees to do this. And if you did indeed have such employees, they could not update the php file which redirects mobile devices to the mobile site as there are too many to remember. To have someone update such file on a daily basis to keep up with mobile devices would be too expensive.

I wait for your reply.