I try to be kind universally to everyone. 95% of the time it is for someone you will never see again, so why bother “making a point”? Not letting someone in front of you in traffic is a dick move, unless, as mentioned, they are swooping around from the shoulder.
OTOH, that 5% of the time you are being kind to non-strangers, like friends and family, THAT is where I tend to have a few more guardrails, as I have found family, especially, will gladly take advantage of kindness, and that is where “making a point” matters, since you will see these people again.
As for the letting people in line - agree it’s insensitive to everyone behind you, however, one exception - if the person is already in line behind you. Say, I am at the grocery store with a basket full of stuff, and someone behind me just has a quart of ice cream - I will let them ahead of me so their ice cream has less chance of melting. No biggee, and no change for anyone else in line.
I will make a stink, however, if someone is in front of me ordering food, and then their late-arriving family shows up all at once to order and they drop in - uh, no!
I get what you are saying overall, but this last statement is unclear to me. How is someone who is taking your time, money, or position, leaving you alone? It would seem they are doing the opposite of that?
Close to where I live there is a county road which typically gets backed up considerably. At rush hour it would typically be 100 cars or so waiting for the main traffic light, I would guess, and only about 15 or so go through the light when it changes, so it’s a long wait. Meanwhile there is also a parallel side street that goes through a smaller more residential type street and joins the main road about 4-5 car lengths before the main light, and some people like to use that road and cut in close to the light. So there’s always the question as to whether you should let these people cut in or not.
My feeling is that people who let them cut in are getting “cheap grace”, for the most part. Because if you’re 4-5 cars before the light and you let a guy or two cut in, then you’re still going to make the light. So you get to feel good about yourself at the price of about 10 extra seconds. But meanwhile, 10 cars back, there’s a car or two who are not going to make the light as a result of your “generosity” and they are going to have to wait another couple of minutes until the next green light. So you’re being this Good Guy when the main price is being paid by someone else.
Though what makes it a bit more complicated is that there are also people who live on these side streets, and by rights they should be allowed to cut in, versus the people who are just taking the side streets to avoid waiting in the same line that everyone else is waiting in.
Problem is that the perpendicular road is even bigger - a state road - and it’s pretty backed up too.
Ideally, they would widen the road(s) at the point of this intersection to allow more vehicles to cross at the same time, but there are structural reasons why this is difficult.
One simple solution would be to allow right-on-red turns at this intersection - they are currently banned. I think the reason they don’t is because of the state road and the state having some sort of formula that calls for no such turns at such intersections. And while if they considered the costs vs the benefits they might override that and allow it anyway, it’s hard to get the state to pay attention to the details of traffic backing up at some intersection somewhere.
I have time, money, etc. but it’s far less important to me than peace. I gladly shed that stuff as needed to maintain my peace. Fortunately, it seems to satisfy most people.