Is tethering ok?

Hello! I'm new here. I don't own a horse, but I do care about them.
I often see horses tethered by the side of the road or against hedges, etc. How cruel is it for a horse to be tethered for days, even weeks, on its own in all kinds of weather? Am I worrying too much? Do horses get bored and lonely? And at which point does tethering become neglect or abuse?

I really doubt the horses are tied for days or weeks. If they are and you can document it, call animal control. Otherwise, stay out of it.

I agree, how can you be certain they are tethered for days or even weeks?

In my book ...NO, unsupervised tethering is never ok for a horse...

Where are you located? In some foreign countries this is pretty common. I would never, ever see that around here (NW USA). I agree with others, not good to leave horse tethered a long time alone. Anything can happen.

I used to tether my mare out usually to eat grass the mower couldn't get at. She was rope wise. When she'd had enough she'd call and someone would put her back in the pasture. I had to tether her or she'd wander off. Not my gelding, I could turn him loose and he wouldn't go far and always came when called.

Thank you for replying to me.
Sadly, where I live in the north east of England, and also in other parts of the UK, horses are tethered for very long periods of time. I totally understand that if done properly by caring owners, that it is probably very appropriate at times, even necessary.
However, there are public areas of land around here where owners will "park" their horses, and yes they are there for days and sadly weeks. I have been keeping my eye on one horse and he has been there for at least 3 weeks now. He has a bucket and he moves around the grassy area occasionally, so the owner must come and tie him up somewhere else so that he can have fresh grass.
But he has been tied up and stands alone. We recently had gale force winds. He has no shelter.
I see a lot wrong with this. It can't be right. But these people sadly get away with it.

I think it is fine if the horse is only there for a short period of time. I do not think it is ok if it is alone and there are no other herd animals nearby. Horses are prey animals and do not usually like to be on their own. I think it can also be useful if you are trying to get a horse used to busy traffic etc. But I also think that someone would be stupid to tie up a horse like this without making preparations beforehand by teaching the horse to tie well and to step on a rope and have him used to rope between his legs etc. The tie point must be extremely secure and not in a place where the horse could get tied up. I live in a developing country and most horses here are kept tethered and alone for 24/7 365 days of the year. I think this is a very sad, lonely situation for a horse to be kept like that all of its life.

Tethering can be part of the horses training,etc etc,and to be fair ,you won,t be watching the horses 24/7,this will be the 1st winter in years I have,nt had one tethered by a road somewhere,

Some communities have to tether their horses. It's very common and indeed necessary for say travellers touring the country by horse and bowtop to have to tie their horse at the side of a road. This may be the only means of securing the horse overnight and also a way of ensuring they are eating plenty before a hard days work pulling a bowtop. I personally don't see anything wrong with tethering aslong as it is done securely and safely and the horse has access to water and grass. Most horses that are tethered are used for driving so this is an essential part of their training.