[mbroncano]

Why aren't they allowed to work in the first place? L2 visas are, and they're quite similar in intent.

[int_19h]

Because US immigration laws have been written in an ad-hoc manner over a long time period, and are very inconsistent as a result.

[cylinder]

L1 is limited to managers, executives or specialized knowledge workers. It's not a low bar.

[xyzzyz]

Most software engineers would qualify for L1. One of the other requirements of L1 is that you need to spend a year in the company office outside of the US. During that year, you will learn some of the internal processes and technology used inside the company, which then will count as specialized knowledge.

[btbuilder]

I know several software engineers who qualified for L1B (rather than L1A) after one year of working for foreign subsidiaries of US companies.

One person was able to transfer to the US after 6 months due to L1 blanket status of the US company. This just requires presenting a form to a consulate and does not require an individual petition to be filed with USCIS first.