I disagree with that interpretation. Evil shouldn't be going out of your way to cause harm, it should be willingly causing harm to get your way. The harm is the method, not the goal.

Like, a good person driving down the road will swerve and crash their car to avoid hitting a dog. A neutral person would stop the car and see if they can move the dog, or at least drive around it. An evil person wouldn't even slow down. Why should they have to be a minute late because some idiot dog decided to stand in the wrong place?

Meanwhile, if the evil person swerved and crashed their car to hit a dog who wasn't even on the road, their car would be wrecked and their journey would be totally ruined. They'd be just as foolish as the good person. If you're going to have your actions bound by the same restrictive moral guidelines as good people in a new coat of paint, you might as well be good.

If while acting in your own self-interest you knowingly, through action or inaction, allow others to come to harm, even indirectly, that is evil.

I think most Americans buy products made via unethical labor practices, and which damage the environment, harming everyone.

Are you really making the argument that the vast majority of Americans are evil?

By that description, the vast majority of people are evil. Well, both evil and good, since most people at least occasionally do things that aren’t in their self-interest to help others. But primarily evil, thanks to the inaction clause on the evil side and nothing comparable on the good side.

They’re also more evil the more educated they are, since they’re more aware of ways that people are suffering harm that they could potentially abate.

For example, if you are not homeless and you are aware that some people are homeless and a storm is coming, if you don’t help them all find shelter - to the extent of bringing them into your own home even if it means you end up not having a place to sleep - by your definition, you’re evil.

I’m not a fan of that definition, either for D&D or anything else, but if it works for your table, great!

Evil isn't the desire to harm others. Devils don't desire to claim people's souls for the lulz, they do it for power. Everything they do is to gain power, for their own benefit. They don't care if the souls will become lemures or a snack, they just try to convince people and scheme for their own benefit anyway.

Demons are way more brutal, they don't really gain pleasure from pain per-se, they also want power, but their approach is way more direct. If they can gain power by killing all those people and bathing in their blood, thay will forcefully do it, not by deceiving the human through a shitty contract, but by forcing their power.

Devils are LE, demons are CE. All in all, evil is the disregard of moral consequences when finding ways to benefit yourself.

Deceiving someone to sign a shitty contract so they now must slave away for you? LE.

Kidnapping someone and forcing them to do stuff to your benefit? CE.

Reaching a fair accord so that you allow people in need to work for you for a fair price, where both parties give a bit so no one is really getting taken advantage off? Either LG or LN depending on the context.

Offering to kill the bad monster that is terrorising the town for free, and disregarding the lucrative offers from it because it's the right thing to do? Any good alignment.

Any of those people could have desires of harm, it's how they channel their wants that puts them in different places in the alignment chart.

Lawful: "the belief that everything should follow an order, and that obeying rules is the natural way of life"

Lawful means you obey the rules. However, presumably you have your own set of ethics, as well as probably the belief in a god that also has their own rules. You have to reconcile these. Obviously if your god is about protecting innocent lives and you think the babies being eaten are innocent and deserve protection, you probably aren't going to obey all the laws in the KoBE.

Nah, there's a whole bunch of Lawful Neutral deities that uphold natural laws, and the Great Balance, like Jergal, Kelemvor, and Mystra. A lot of Good/Lawful Good deities as well, especially when it comes to the natural passage of life and death. Messing with that natural law gets you on the wrong side of like half of any given pantheon. There are even evil gods, like Bane, that are all about law.