But what about rot?

Concrete is porous and not waterproof on its own. This creates the possibility of the wood being moist for an extended period of time. Any time the issue of embedding structural posts in the ground comes up, people rightfully point out that moist wood will tend to rot. However, this approach is permitted per code. California Building Code § 1807.1.4 states, "Permanent wood foundation systems shall be designed and installed in accordance with AWC PWF. Lumber and plywood shall be treated in accordance with AWPA U1 (Commodity Specification A, Use Category 4B and Section 5.2) and shall be identified in accordance with Section 2303.1.9.1."

Direct embedding of wood is common in pole-barn construction as well as utility poles all around the country.

Perhaps most importantly, some providers of treated wood are willing to provide warranties. This ecolife wood, for instance, comes with a lifetime warranty against fungal decay and termite infestation.

Additionally, the concrete, which protrudes 6" above the ground, provides additional rot protection beyond what is required by the code or the wood treatment warranty.

But what about rebar reinforcement in the foundation?

Rebar reinforcement in concrete is provided for two main reasons, firstly to reduce cracking and secondly to provide bending strength for the concrete member. In this application, the wood post is strong enough to provide all of the bending strength required, and small cracks in the concrete below the ground surface are not a problem. Therefore, the foundations don't require any rebar below the ground. One or two #3 stirrups at the top of the foundation will guard against visible cracking above ground.

Cantilever wood carport structures are cost effective and ecologically friendly, and we ought to be seeing more of these simple projects.