This topic has been discussed already, but it's worth to re-state them.
We already have a very little salary for everyone (granted by Sauron).
All scripted jobs have already a salary system based on how much you work. That's the best system we can use in my opinion, as only really working you can get your money.
You may say: "yes, but most times I chase suspects (in the case of a cop) but don't get them! = no money"
You're right. At the moment LCPD isn't very developed because of server problems and limits.. I'm telling that because I was used to get a monthly pay as SAPD Officer (but also freecops in the department got it..) in SA, but this is not happening here. Not yet.. or just will not.. who knows...
Anyway, as Kerbe said already, giving out a pay based on just being on duty (not counting the work done) will just make the scoreboard full of blue names.. nothing more.