Tesla has more scale and a gigantic gulf of data against waymo, who's widely considered their biggest competitor in the space openpilot as just a software company also has to find a scaling solution in order to compete with a company that has millions of cars on the road collecting data for them 
people have to hear about, buy, install, and use their software in order for their machines to learn, improve, and iterate 
when you say that openpilot is "as good" as tesla's current generation of FSD, what you mean is that 2 = 2
as in level 2 autonomy is level 2 autonomy
but the scale of levels of autonomy is arbitrary
somebody literally made those levels up, and you can condense or expand them to an infinite degree based on preference
level 2 just means that by a company's definition, "the driver must remain alert and is required to actively supervise the technology at all times.", whereas level 4 means "autonomy does not require any human interaction in the vehicle’s operation because it is programmed to stop itself in the event of system failure."
that's not a statement about the capability or performance of the AI, it's a statement about the measure of safety that an organization feels in allowing the AI autonomy.