It was cold across much of the U.S. Thursday morning when the Apple (AAPL) iPhone for Verizon (VZ) finally went on sale.

But you can’t really blame the weather for the turn out, which Business Insider characterized as “laughably short.” Apple enthusiasts have camped out for up to week in front of Apple’s big glass cube on Fifth Avenue — braving rain and cold and humorless security guards — to be first in line for a product they really cared about.

But when my colleague David Goldman at CNNMoney arrived at the Fifth Ave. Apple Store at 6:45 a.m. this morning, he found only eight people waiting to get in: six former T-Mobile (DT) customers and two from Verizon. A ninth buyer, an AT&T (T) customer with an old iPhone 3G, showed up at 7:10.

Why so few buyers? I think RBC’s Mike Abramsky had the right idea Wednesday when he listed seven reasons Verizon’s Q1 2011 iPhone 4 activations would be less than AT&T’s in Q3 2010.

His list, lifted from yesterday’s post, below the fold:

• The iPhone 4 at Verizon is new, but not novel (vs. when AT&T first launched its version of the iPhone 4).
• A lot of existing Verizon customers with Google (GOOG) Android phones are still on contract.
• AT&T offered customers an early upgrade option; Verizon did not.
• There are a lot of AT&T iPhone owners who might like to switch, but are still on contract.
• Verizon’s data plan ($30/mos.) is more expensive than AT&T’s $25 and $15 offerings.
• AT&T’s first-quarter iPhone 4 sales covered 13 weeks vs. Verizon’s 7 weeks.
• Some potential Verizon customers are holding out for the iPhone 5, expected to arrive this summer.

Also on Fortune.com:

• Verizon iPhone: The reviews are in
• Rate plans: How AT&T, Verizon, Sprint and T-Mobile stack up
• Survey: 44% of Verizon Android users likely to switch to iPhone on Day One

[Follow Philip Elmer-DeWitt on Twitter @philiped]