The difference between a lawyer on the one hand, and a "jailhouse lawyer" (an engineer who does legalish work) on the other, are these:
The lawyer knows how to get things done to support the business. It's rare for a real in-house lawyer to tell the business, "we can't do that." More often, it's "here's how we do that."
The lawyer knows how to write a form contract (sales, lease, nondisclosure, etc) so other lawyers will read it and say "ok, that's fair" and sign it.
The lawyer knows how to read an incoming form contract to see if it's fair.
The lawyer has real relationships with her counterparts at customer and vendor companies. When a vendor tries to change terms, she calls her counterpart and asks, "what's this about? My business has problems with this. How can we get to yes?"
The lawyer knows that if a dispute gets to a judge, the remedy will be money. With very few exceptions there's no way for a judge to repair a business deal that's gone sideways. So the lawyer says, "anything but court."
At some level, the law is like computer code. But the computer code has been around for many centuries and it has been patched over and over and over again as needed to solve real-world problems: in the US and English system that's called "case law.". There's an adage that "hard cases make bad case law." Lawyers know the ins and outs of this stuff.
In my experience as an entrepreneur, when I've played lawyer I've generally overdone things to my detriment.
The US is definitely litigation-happy. That makes things tough.