I appreciate the sentiment, but in this case, it's not completely "just wood":
I think the point being made was that a lot of things that we think of as outside our domain of expertise, and thus inaccessible, truly aren't.
It's worth attempting to construct the garden bed yourself, and you might find that it's not nearly as insurmountable of an obstacle as you'd imagined. In this particular case, treating the wood might have been part of the process of learning how to make the garden bed, as would using a saw, polishing the wood, etc.
Untreated will not last. Treated will potentially release chemicals into your soil/food, though you can line the interior of your bed with gardening plastic.
There are also slightly more expensive options for treated wood (branded EcoWood and so on) that are a good option.
(I have seven 1.2x2.4m raised beds in my garden. Bring in fresh soil otherwise you will get endless cycles of weeds - that's still one of my main problems two years in.)
Untreated pine is also a risk when it comes to termites.
But I agree with the spirit of the original. It's just a raised planting bed. Use it till it falls apart, then make another, using the lessons you learned the first time.
I am with goose, it looks like cedar. If that is pine it has been curing for a year.
2x's are commonly eastern white pine in many parts of the country (or "SPF" -- spruce/pine/fir, no promises, but not douglas fir). DF is sometimes also available, as is SYP. Both are more expensive than WP, slightly.
4x4s are always DF, in all locations that I've noticed. No doubt due to its superior straightness and strength.
Also curiously 2x3 availability (always WP, afaict) varies greatly. I've had lumberyard guys stare at me like I was crazy for asking where the 2x3s were. These weren't new kids, either.
All of these variations might be influenced by local building codes, in addition to regional distance-to-market.
As for the species in the photo... Could be cedar, but the grain looks pretty tight -- another possibility would be redwood, which is appropriate for the use, and is available at west coast lumberyards. Can't get redwood on the east coast except at specialty yards, and even they generally don't stock it.