Hollywood does it that way. They're heavily unionized, which gives the workers some bargaining power. Construction used to be heavily unionized, which made per-project employment not too oppressive.
To see how unions can work in software areas, see The Animation Guild, IATSE Local 839, which represents most of the people who make animated and CGI content in Hollywood. They have a standard contract and minimum rates for different jobs.[1] Most projects pay more than the posted minimum; that's negotiable. The lowest rate for any job under the union contract is currently $31.50/hour, for an "inbetweener" in the first 6 months of work.
There are also provisions which keep employees from being jerked around. A basic feature of Hollywood contracts is that there may be situations that require extra work, even extreme hours, and all that costs the employer. Time and a half after 40 hours or 5 days. Double time after 14 hours, including meal breaks. Any day where work is required must be paid for at least 4 hours. (This is why film scheduling and budgeting is a real discipline while software scheduling is a joke.)
[1] https://animationguild.org/the-guild-contract-one-year-in/