I The summons isn't sent return receipt requested, they can't prove that you actually received it, and they'll go a couple of rounds of you not responding without getting really serious about it.
Of course if you push it for long enough, they'll probably play a bit harder, but ignoring one, or even two notices isn't going to get their attention much, they'll just figure you are away from home or something.
My MIL did that and ended up with a bench warrant for her arrest until she served. Then when she did serve she ended up on a sequestered jury!!
She never let it go again!