[jlaurend]

Some places have a contract-to-hire approach which is effectively a trial period.

I believe companies fall into two basic structures:

1. agency / consultant model - implement short-term projects, specific tasks, etc. It's easier in this approach to swap employees in and out as new projects start.

2. software product model - the company's entire business model is built around or highly dependent on internal software projects. Institutional knowledge is very important. It's really important to protect the product process and plan for the long-term implementation of strategic vision.

Contract-to-hire works well for #1. But for #2, the overhead and cost of disruption to the core process is too high. Top-tier software products require a relatively smaller number of highly engaged and skilled people to drive projects to an optimal point. These people need to also be directly involved in hiring and onboarding to maintain the culture and high standards. Bad hires can destroy such a team. Thus you end up with the current interview processes as they're efficient and err on the side of rejecting qualified candidates accidentally. If they spent 10x as long on hiring, they could improve the accuracy, but then they wont have as much time to build product which is the key tradeoff involved.