Why are stock prices delayed?

From what I understand all the tickers I can access for free on Google Finance and Yahoo Finance and (I believe) even through my value broker site are delayed a bit. Why? I know you can pay for access to "instantaneous" prices but in this day and age what keeps it from being free?

What site gives the least delayed numbers for free?

Thank you in advance.

EDIT: Ok, so everyone keeps telling me the sites I'm looking at are not delayed. But when I look at two or three of those sites simultaneously they don't all have the same numbers at the same time so SOMETHING is causing some delay. The only real explanation I guess is maybe these sites aren't deliberately delayed, so I guess there I go. I'll have to watch and see which of the sites available to me is closest to real time.

Thanks, r/Stockmarket.

Submitted August 26, 2016 at 01:42PM by MellowMickSnowed http://ift.tt/2bUWraV