Ok, I've ran the test and it confirmed my assumptions.

I've created a user called "redis" and then installed the `redis-server` package.
During installation it creates a directory with files /var/run/redis or /run/redis that is owned by the user "redis".
So as the redis user I can now edit those files directly.
The daemon is also run under the same username.

Quote:redis 4121 1 0 08:13 ? 00:00:00 /usr/bin/redis-server /etc/redis/redis.conf

Now, what if someone creates a program and name it "john" and runs the daemon as john and it suddenly gets popular and people install it all over the places.