They don't.
A .22 pellet weighs about 15 grains.
At 1,200 FPS it carries 47 lb/ft energy at the muzzle.
A .22 LR solid bullet weighs 40 grains.
Hollow-points weigh 36 grains.
Look for 120 - 130 lb/ft energy with them.
And longer range, flatter trajectory because the heavier bullets retain velocity much further.
I agree with this except for the last sentence. Tragectory has nothing to do with the weight of the projectile and everything to do with the initial velocity and the ballistic coefficient of the projectile. I've done the math. I don't know what the ballistic coefficient of the pellet is, but I suspect it leaves a lot to be desired vs a .22LR heal seated round nose. So, the answer's still the same, just disagree with the cause. Somewhat moot to the discussion, though.
I've killed squirrel to 25 yards with an old benjamin pump up .22 caliber pellet gun I got for my 7th Christmas...would be 53 years ago in November. That gun quit working, needs refurbishing, but it worked fine when I got my first chronograph 30 years ago and only clocked something over 400 fps. I don't know what a modern .22 caliber air rifle can do now days, but 1200 is a good velocity for a .177 caliber gun. I don't know that a .22 would do that, but I simply don't know what's on the market. I have a cheap .177 and it doesn't clock the 1100 fps it's advertized. Must have tested THAT with a magnesium pellet or something, maybe polymer.
Anyway, inside 25 yards even my old Benjamin was death to squirrels. Modern stuff just HAS to be better.
I'll keep my .22s, though. I have some stash and bought a box of Eley Match yesterday for squirrel hunting with my 10/22, really shrank the groups. Head shots at 50 are now possible, hell, eyeball shots.
It's the only .22 LR I've been able to find and it's 19.95 a box of 50. But, I won't shoot tin cans with it so it should last a while. I've got a stash of about 700 rounds of .22 short I found a few months back that I'm using up in my old Remington bolt gun for plinking.
I'm thinkin' this ammo thing is about to ease up. I keep seeing more and more centerfire on the shelves everywhere. Only a matter of time and I'm hoping to get a few 550 round boxes of Federal, my favorite plinkin' ammo. I'm nearly dry of that stuff.