Is a manufacturer required to provide schematics to their gear?
Absolutely not.
Well, that's about the silliest question I have heard.
It may be naive but I do not think it silly. I have usually tried to get a service manual and schematic for my equipment, especially if I plan to keep it for a long time or if I have thoughts of modifications.

A few years back, I had an input noise problem with a Pioneer Elite tuner and I asked a local dealer/tech if he would look at it for me. He said that it would be pointless without a schematic because of the complexity of that unit but, when I said that I had the service manual and schematic, he readily took it on. Cost me 1 hour of his time and about $10 in parts. That was 12 years ago and the tuner continues to work superbly.

Schematics are a business all by themselves...
And NO , I do not think the company is required to even provide them for sale.
I am certain a lot of small companies just do not create them. The big ones used too.. but who knows anymore?
A few companies offer them for free in detail on line.
So it is all over the place.
Used to be SAMS photofacts offered all of them for a price.. but even SAMS is falling apart.
But you want a TV schematic for a 1953 Philco... go to SAMS... A 1972 Realistic eight track.. SAMS...
Congress hasn't gotten around to requiring that yet, as far as I know.
No. It's the manufacturer's intellectual property.
I was asking because a friend claimed that he was accustomed to getting a schematic in his time, he is much older than most of us.
I understand that it is a matter of protecting ones intellectual property, but most electronic equipment can be reversed engineered, so those that want badly to illegally copy will manage to find a way, and the hobbyist who doesn't have the resources will be stuck.
I would think the proper course would be to provide them when the unit goes out of production. When I was a Meridian dealer I could not get a schematic for the 605 amps I was using but I recently requested and received one as they are no longer in production. I have not been a dealer for years. Some companied just want to corner the repair market on their products; I have this problem myself with a couple of units; I am quite willing to pay for the schematics of the products, which are discontinued. If they won't provide them I have a technician friend who can repair them anyway, it will just take longer.
Those are the same feelings I had when asking the company for the schematic of their amp. They kept insisting they couldn't find a copy of the schematic. What does that say about the company when they can't produce a schematic of their most popular amp, of course it was a nice way of saying we don't give out schematics. My technician just as yours can repair it anyway so I will have the amp fixed by him anyway.
I have schematics for my older equipment including CJ, but I have not been able to get schematics lately from Audible Illusions.
Distribution of schematics is 100% up to the company, as a previous poster quoted: they are that company's Intellectual Property.

In this day and age of offshore manufacturing and all the copying and cloning going on, I would suspect that acquiring schematics will only get more difficult in the future.

I work for two foreign manufacturers (dCS and Nagra) and am also McIntosh, Plinius and a few other brands authorized, and none allow me to provide schematics to end users or non-Authorized service providers.
It would be nice but I would think not especially if patented design or asic/custom parts are involved.