The ping that is displayed is not from them to you, it is there ping to the server. You technically don't have a connection to any particular player because the data is routed through the server to you. It all depends on your connection to the server and their connection to the server.
The MTA Team definately will make things better as the work progresses; look how much better things such as aiming and driving have become now.
actually, you do have a connection from player to player, i remember playing with IJs and Aeron, we all had a low ping but IJs saw me and Aeron lagging (aeron and i have the same isp, IJs has a differnt one) while Aeron and i didn't see eachother lag, but we saw IJs lagging (IJs even had the lowest ping) so somehow there is a connection from player to player somewhere