I would have to say that some I own are not uniform out to 180, but are visible past 180. One of them is.

I have a couple of Rabot 1000 lights with a clear housing, they are visible well past 180 degrees. The Planet Bike Superflash is too. But not as bright as behind. Some can be seen almost from the front.

I also have a couple of Cateye 1000 lights that have two led's on each side pointing directly sideways (180)
and are visible past 180 . and full power at exactly 180. The new 1100 replaces it with brighter LEDs.

I had some that had an LED pointing 45 degrees on each side. The old planet bike 7 LED blinkies. Gave them away, they were pretty old, and not modern LED's.

There are older and brand new lights that are visible past 180. Unfortunately some of them need to be tested to be sure. I think the Cygolight Hot shot, and, Hot shot 2 have good side visibility, but I don't have one here right now to look at.

It surprises me that so many tail light owners never test the tail light at night by standing the bike somewhere at night and walking way behind it to see rear and side visibility. I know many forum users like you and I do.