Whilst it is only residents, those whose permanent home is Spain, that should be on the padron, many towns, especially those with a very high number of non residents, allow non residents to be on the padron. Their argument is that the rules say it should be your permanent place of residence but they say it means your permanent place of residence in Spain. Not wishing to go in the rights or wrongs of that (despite scare stories of thousands of euros in fines I've never heard of anyone being fined) the municipality gets a grant to cover all those who live in the town for things like road improvements, local policing, extra facilities and so on. A town with many, many non residents will still have to provide the facilities but won't get the money from the regional government to be able to do so.
That bit posted says non EU who are not permanent residents (which you get after 5 years of residency in Spain). Non EU citizens are supposed to have residency for 1 year, renew it for another 2 years and then renew it for another 2 years until they become permanent (which we didn't have to do in the EU). I think that applies to the padron as well.
The padron, for permanent residents, lasts for 5 years but, if you need it for any official reason, it must be in date by 3 months. For example, apply for an initial TIE and you need a padron dated within 3 months of application. Apply to exchange your old green registro card for a TIE and you don't need a padron at all if the address is still the same.
Many places give discounts to those on the padron (for example, the ferry from Mallorca to Ibiza is 60 euro but only 6 if you are a Mallorcan resident on the padron).
The town gets a grant from the regional government depending on how many are on the padron (good for the town and community).
Our local town hall runs free Spanish and computer lessons for those who are on the padron.
Residents, temporary (under 5 years) and permanent (over 5 years) can vote in local and regional elections but not European or central general elections.
If doing something like taking out a loan, buying a car etc where proof of address is required, a padron certificate can be asked for although, as many places don't allow you to be on the padron if it isn't your permanent home, house deeds plus utility bills now seem to be accepted.
In our town, they do allow you to be on the padron if you are a non-resident. You can also just turn up and they will renew it for you if you need it for something. Other places, Torrevieja for example, have a 2 or 3 month waiting list for an appointment.
You can't get a SIP card for your health if you aren't on the padron. The padron will show which surgery you come under and will allocate you to that one plus a GP. If your padron runs out (after 5 years)and you don't renew it, you could be removed from the surgery list and a few people, Spanish as well as foreigners, have complaine in the newspapers that that has happened to them. No longer registered when asking for an appointment.
In these Covid times, there are many people without a SIP card as they are not eligible for an S1 and rely on private health even though they are residents. Showing your residency card (either one) plus a padron and mobile contact number at your local surgery will get you a temporary Covid SIP card so you will be on the list when they call you for your vaccine.
When you get older (sigh, I'm already there) you can't get access to social services or home care unless you are on the padron. (A Norwegian couple in their 80s across the road from me got a district nurse calling on them to give them their covid vaccines and one of my neighbours had a serious operation a while back and a nurse called on him at home every day for a month to check on things and change dressings etc).
If you aren't elderly but have kids, you can't enrol them in local schools unless your padron is up to date.
Probably loads of things that we don't know about.