E.g. a company that uses people to calculate taxes is not tech, whereas a company that uses people and software to calculate taxes is a tech company if their use of internally-developed software gives them a significant competitive advantage over other companies in that market.
EDIT: Thinking about it a little bit more, a vegetable growing company is not a tech company unless they use software to drive down expenses so they can compete better, allowing their investment in software to give them a greater rate of return than a comparable investment in additional people/other capital. Typically the automation system is also licensed for sale externally at sub-linear marginal cost. This means that tech companies benefit from a faster rate of growth than a traditional capital-intensive business, while driving up productivity in their market.