Actually yes it totally does. The problem is, you didn't think it through. With mIRC, you are paying for an "upgrade contract" that is, upgrades are included in the fee. With Windows, you have a "single title contract" that is, you just get that one version. However, MS does sell "upgrade contracts." Do you think companys/schools/governments are gonna go down to the local software store every year or so and buy a few thousands CDs to upgrade their software? Of course not, they get an upgrade contract from MS. Thats what I have. The one I'm in is through my school. The school has a contract with MS where they pay a set fee and you can get free upgrades (I think it costs the school something like $8000 a year). To cover this, the school then charges students who wish to participate. So I pay my $80 and I get all the free updates I want from MS because instead of having a "single title contract" I purchased an "upgrade contract."
You're right you can't compare mIRC to Windows in the standard sense because they work differently, but if you pay the licensing fees, the Windows works just like mIRC.