Hate to nitpick, but is code really the #1 asset of most software companies?
if AWS/Amazon's entire source code were leaked tomorrow, how would competitors use it to their advantage?
Would it help Lyft at all if they gained access to Uber's source code? Probably not.
Is some startup going to be able to take Slack's source code and use it to build a competing service? Probably not, it would be easier to write the code from scratch and reverse engineer features.
Source code is definitely a company asset, but most companies wouldn't be incredibly damaged or threatened in any meaningful way if their source code were exposed... unless said source code exposes security flaws that are used for some attack on the service. But security through obscurity (e.g. keeping insecure code secret) is not a valid way to keep things secure.
Leak of code can be very damaging, not just because it might reveal vulnerabilities but also because it will reveal IP and will allow all sorts of 'IP theft'. Then, losing the code altogether is the death of the company.
I guess my point is that for 90%+ of software companies, you can very easily reverse engineer the software or just rewrite it from scratch.
If I were given $50 million to build a Slack competitor, even if I had Slack's source code I can't imagine it would be that helpful. More than likely it would be easier to rewrite and re-architect in order to not inherit all of the technical debt of very old software.
Not to mention in most cases, access to the source code doesn't mean you can easily recreate the AWS / Google Cloud / Azure environments necessary to run the source code reliably with scalability.
Edit: There are obvious exceptions to this, but most apps these days don't require a whole lot of proprietary algorithms that can't be easily cloned without source code access.
There are instances of an overseas company stealing a large amount of code and just running it as-is.
As long as you do it outside the jurisdiction of the USA, you'll probably get away with it.
I have seen two instances of this in my professional career (can't talk about either I'm afraid!), but in both cases it had a pretty big impact on the original owner of the code, and in neither case did the company manage to get any compensation.
For a software company the code repo is the #1 asset.