Documentation and getting to build/use it feels to me like support, and I feel that needs to be billable. The source code is the raw product, which is also of value/crown jewels. But it is easier to give it to someone, then to support it.

So can the government force companies to assist them and to what extent? From the article it is suggested that Dell, Huawei, and Juniper have already done so.

But how where they compensated, because engineering time is not cheap, or where they given software backdoors and told to integrate them.

I don't think we will ever know. But would be interesting to know how managers had to explain to the bean counters, that limited resources was spent on project "top secret" instead of a real project making money.

> ...and I feel that needs to be billable.

They get paid. Telecoms do as well, they actually have billing schedules for wiretaps.

> ...managers had to explain to the bean counters...

You've got it backwards, the lawyers explain to the executives who then explain to the department head who then explains to a manager who then explains to a senior team leader who then assigns the work. At the end of the telephone game it looks like any other incomprehensible contract requirement.

It's hard and really expensive, I don't think any big company would like to do that. For large shops, source code building is non-trivial. It may require proprietary toolchains, metadata stored in some other dbs, or specific hardware / environments. And the toolchain may even not work outside the shop, e.g., depending on internal infras.