If you add unique open graph content to each page it can be time consuming.

Eh, these prices are what Crew charges for these services. This is actually little more than a glorified pricing calculator for that agency. This isn't a real price guide.

If it was you, you'd probably charge less. Personally, I just clicked through this for a project I'm working on and the actual amount I'm getting paid is only ~15% of what the Crew would apparently charge.

I don't think they are literally saying social buttons cost 1300 bucks. I think this is more so trying to make the point to potential clients that more stuff = more time = more money.

It would be impossible to cover all of the variables of what a client might ask for. However, by including something simple and demonstrate how it increases the price, it says to the client "hey, adding this going to take more time than not adding this." You would be insanely surprised at how many clients do not understand that.