That's true of software generally, but not will not be true of automated driving software.
Windows, iOS, Facebook and YouTube have strong network effects. Google search and Microsoft Office offer a familiar user interface and superior features.
Self driving software will have none of these benefits - there is no network effect, no significant user interface, and no feature differentiation. As soon as there are 3 self driving software products on the market that meet minimum safety standards, competition will force the price down to little more than the cost of development. What's more, that cost of development will diminish over time: If in 2027 a company decides to develop self driving software, the development cost will be much less than the $1.1 billion Google has paid. So over the long term the economics will be similar to airlines - suppliers offering a commodity product and generating thin margins.
Although the long-term trend is bleak, Waymo does have two short-term advantages: 1) possibly being first to market; 2) its suite of patents on self-driving tech. Personally I don't place much weight on these advantages so I would value Waymo much less than the stock market. As an Alphabet shareholder I very much hope that they spin off Waymo so I can sell my interest in self-driving tech.