There is a gametype available for you to play where you dont need to worry about friendly players running into your bullets, nades, scorestreaks. Its called CORE.
Now the regular hardcore players understand that your all trying hard to get your diamond camos for the weapons that lets face it, suck in core. But that in no way means that the game needs to be changed because you cannot adapt to the rules. Here is a few tips to help you in these trying times.
Random nades are bad. Unless you are sticking it into an enemy's back pocket dont take them out. Same goes for noob tubes and rockets. This one rule will save you alot of heartache.
AOE killstreaks are bad. Unless you are playing as a coordinated team the risk to friendlies is very high. Switch them out for something more controlled. Choppers, sentries, and guardians can wreck havoc in hardcore and last longer.
Watch the high traffic areas. These same chokepoints bottleneck with friendlies as well as enemies.
If you are not seeing the friendly tags you have 2 choices either learn to identify enemies by their uniforms or backout and find a better lobby.
If you have just spawned and you take 4 steps and stop to fire there is a good chance that someone may run past you especially if you stop in the open.
Play smarter not harder. Hardcore is tough and its meant to be that way. The regulars accept that risk for the rewards of being able to get the drop on someone and not having to worry about bullet sponge syndrome. Besides if you cant hang with the big dogs go back to pissing like a puppy.