Are the other tenants paying less rent because the rental market generally is lower than her previous agreement?

Her agreement with the landlords is independent from the leases the other tenants have signed. And in my city, if the landlord upgrades something, they are often allowed to pass on the cost to the tenant in the form of higher rent. She may not be able to force them to do anything.

it may be that the only thing she can do is find a new apartment., or research the market where she is and offer proof of how much less rent she can pay (and how nice a place she can get) if she does move. Then, she can threaten to move, and tell them she'll stay if they'll give her new carpet, appliances, etc., for the same rent.

She can point out that if she DOES move, they'll have to replace the carpet, etc., anyway, to attract a new tenant in that market, and they probably won't get as much money (bcs no other new tenant will pay more than the market rate, esp. not for a worn apt.), plus they'll have down-time when the apartment will be empty between tenants.

Then, if they give her new carpet, she can stay; if they don't, she'll have a new place to move to, hopefully w/ newer stuff and a lower rent.

The only other regulations you might be able to find are, in my city, there's a regulation that (in bldgs of a certain size) the landlord must paint every so often; there might be one that says carpet must be replaced every 10 years. You might call whatever agency would regulate this in your state or city, and see if they have any info--it will be city or state-specific, and may be buried deeply enough that just talking to someone at the agency will be faster.

What state and city does she live in?

It may be the landlord is hoping she will move. Then he will have an empty apartment to redecorate at his convenience so he can rent it out at a higher profit. There is a lot of cold blooded calculation in the rental business.

I had a similar situation. The new owners went out of their way to make a total mess of my apartment when making repairs. I gave up and moved. Now, I moved my possessions out before the lease was up. The next morning I went back to get some items, and to hand in my notice. Surprise, the owners had workmen and scaffolding in my apartment and they were already replastering.

Later the very nice but frightened resident manager told me that after all units were remodeled, the new owners sold the building for a quick profit and moved on.

I have lived in my apartment for 4 years. The complex was recently bought out by a new management company. About a month ago, they began advertising here on the property, as well as on their website, that their apartments are being upgraded with brand new appliances (replacing 20 year old ones), wood floors (replacing dingy carpet), and granite countertops (replacing laminate). They don't say, "in select units." So I was pretty excited! I stopped by the office to find out when they would start installing all of this and I was notified that they are only providing this for new tenants and upgrading each apartment as it becomes vacant. And when I checked the website, I noticed that they have lowered the rent for the new tenants even WITH all of these upgrades. I am not as frustrated with that as I am with the fact that they are advertising all of this and not even offering it to their longterm tenants. Isn't this false advertising? Is there anything we can do as current tenants? I would really like those amenities!! I have written a letter to the management company asking about this, as well as left two messages, but it has been two weeks and nobody has gotten back to me. Any thoughts?