How often has it happened to you that you were running late for work, rushing out the door, only to get in your car and have it not start? I'm sure it has happened to everybody at least once, and on Long Island the absence of a car means that, basically you're not going anywhere.
The lack of mass transit on Long Island poses a big problem because we are so sorely lacking enough buses, train routes to make mass transit a truly viable option for most people. Sure we have the LIRR but how helpful is that really when you're on the South Shore and need to get to the North Shore? To make this happen you would have to go all the way to Jamaica to change stations, turning what would have been maybe a 20-30 minute ride by car in an 1-1 ½ hour expedition. The bus situation is no better. Even though there is a wider variety of routes it still doesn't cover everywhere, and when buses are an option they are an excruciatingly long one, turning a trip from my house in Lindenhurst to the Massapequa mall(normally a 10 minute trip) into and hour affair.
Now the true question arises as to what can be done about this? How, one might ask, can New York City have such and efficient and well used system of public transportation, yet Long Island right next door is inadequate? To me the basic problem that makes Long Island harder to have efficient public transportation is the sheer size of it. Size-wise, as a whole Long Island dwarfs New York City. It must be much easier to have and efficient bus system when you're running from one end of tiny Manhattan Island to another, then running a bus from Uniondale to Quoge. .
As for underground subways like the city has, this is simply an impossibility on Long Island. We don't have the same geological makeup as Manhattan which sits on Granite rock. It would be much more difficult to try to dig out the sandy, often waterlogged soil that Long Island sits on.