Car rentals

Planning a trip to the US, I looked into renting a car. I haven't booked yet, but I did send the following email to ALAMO:

Gentlemen:
I checked the prices for renting a car for two weeks and I discovered that it costs several hundred dollars more to rent from you, Alamo, if I reside in Israel instead of the US.
Obviously, you have some logical reason for this; what confuses me is that, according to the their websites, Avis and Budget have CHEAPER rates for residents of Israel than for US residents.
Please explain why you charge more for residents of Israel (while other US car rental companies charge less).
In case it matters, I have a valid Massachusetts drivers license and I am a US citizen.
Yours truly,

I don't see myself as a consumer advocate, but I am curious...

By the way, regarding the previous post about Israel's phone company, after several weeks I did receive a form letter from Bezeq thanking me for my inquiry and assuring me they're looking into the matter.