What explains the increased use of the initiative process in the past few decades?

What will be an ideal response?

Varies. Mentioned in the book is the development of signature-gathering firms, which make it relatively easy for groups to collect enough signatures if they can afford the costs, which can run into the millions of dollars. With respect to California's political culture, using direct democracy to exercise the "power of the people" (often to "get around the legislature") is generally acceptable, a pattern that was re-established in 1978 with Proposition 13, the famous anti-tax measure. Also, vote requirements are regarded as being relatively low in a state as large as California, and signature collection is relatively uncomplicated (there are no requirements to gather signatures in every county, for example).