Reasons for the inconsistency:

1) "TSA is a new agency and these things take time". (Of course, I've seen new signs and videos put up in the last year that still contain the old information. And everyone knows that changing/correcting a single piece of data on a website is so hard).

2) "Inconsistency is TSA's motto". Yes, that will fool the terrorists - they'll get so confused about the rules that they'll make a mistake or get frustrated and give up.

3) "All nations are equal, but the US is the best". We're still waiting for the rest of the world to get its act together and get off the metric system.

BTW, the change to allow 3.4 ounces instead of 3 ounces was absolutely not out of consideration for foreign travellers - it was because there are many products that Americans use that are manufactured and labelled to world standards, ie, metric.

And yes, there are the occasional TSOs who don't get it and who require pax to forfeit containers labelled 3.1 ounces because it exceeds "3-1-1".