It's not so obvious that they can't. The only caveat might be that the repurchase might have to take place on a foreign market, meaning that the shares would have to have a dual listing.

Actually it's black letter law. Where the share are "listed" is irrelevant. They are shares in an American corporation and cannot be purchased with un-repatriated profits. If the behavior of hundreds of corporations in 2004 (which brought back the profits under Bush's tax holiday and then used that cash to buy back shares (why would they have waited, otherwise), then perhaps this explanation from a Legg Mason presentation will convince you. Look on Page 8, please.
http://www.lmcm.com/908178.pdf

Are you aware of the benefit of donating appreciated stock from your personal portfolio (it cannot come from an IRA, 401(k), 403(b), or other retirement account), rather than cash, to a charity? First, you don't realize the capital gain, and thus don't owe taxes on it, and, second, you get to deduct the full appreciated value for donation.

Yes, but so what? The fact that there are quirks in the tax law in one place does not mean that your original thesis is correct. It's not.