Hell, I'd be thrilled if I could get 10-15K out of bike tires, instead of half of that, or less . . .
John has it mostly right. Larger flat contact patch, plus harder rubber, plus heavier carcass and belting, plus four tires to share the load all contribute to longer car tire life. Heat is the enemy of rubber, and tires flex during normal operation, adding heat. So car tires are built harder and heavier to counteract that, and to deal with the additional weight of a car.
Note that even car tires come in a variety of compounds. You can get sportier tires that stick well but wear faster, and harder tires that last but give less grip and a harsher ride. Most drivers are fine with longer-wearing tires, as they don't usually push a vehicle's limits. But some drivers prefer the sportier tires, and just change them more often, much like some riders do.
By the way, contact patch can affect tire wear, but it doesn't affect traction. The formula to calculate friction is:
= μ Fn
is the Force of Friction (usually calculated in Newtons), Fn
is the Normal Force (weight of an object pushing down against a surface, also in Newtons), and μ is the Coefficient of Friction, based on the surface treatments of the two objects (but always less than 1.0).
Surface area doesn't appear in the formula at all, and so isn't relevant to the friction calculated, or to the traction we see on a bike (or car) tire. So a larger contact patch when leaned over has more to do with evening out tire wear than it does with increasing traction.
And that concludes the Physics lesson for this evening.