Pedestrians' heads are ALWAYS OB. Sidewalks are OB at the discretion of the TD who ALWAYS has disc-retion.
No, I did not say that.
It's always the ruling of the TD in the case of tournament play. I believe that if not stated they are OB, but have played in an amateur league that plays them inbounds. I say make up the rule between yourselves to play it in or out and go from there.
Maybe I am in the minority here, but I kind of like mando's. Mostly because it adds a level of difficulty to holes (at least around here). They ensure that you take the designers intended route, and not (for example) through trees that have drastically thinned out since the courses "birth."
Also, mr. osbogslejuld...i won 19 games of Call of Duty 4...in a row. And that was in 2008, so take that!
...The Gold Course at Winthrop, home of the USDGC, shows others feel this way too; playing in the USDGC is highly coveted for many reasons, but the course is one, and many who don't get in are eager to play the course while the ropes are up.
How many tournaments are held where there are a ton of sidewalk? I would guess most are in disc specific areas that do not have a lot of walking paths in the middle of the course.
I know in ball golf, if it lays on the cart path you can call it 'unplayable' and move it a club length (maybe 2 club lengths) with no penalty, then play from there.
No closer to the hole though, only perpendicular or farther away.
That would most likely be so you don't ruin your clubs.
Ball golf designers can build lakes (effectively OB) and sand traps just about whereever they want.
Disc golf designers must take what they can get. Sometimes this means having to incorporate sidewalks, roads, etc., because that's the only place the parks department gives you. Sometimes it means the parks department comes in after the course and adds walking trails, and there's not much the disc golfers can do about it (I'm very familiar with once recent case of this, and another coming soon). Sometimes, when you can't create features, you find them and use them as best you can, and this may mean making a sidewalk O.B. to enchance the challenge.
Personally, I've played great courses with lots of OB and even "island" holes, and great courses with no OB other than leaving the property entirely.