I think this debate keeps coming up because of the experience of a few early kickstarters, who had no real clue as to how much things would cost to produce and then later wrote postmortems where they moaned about losing money on the physical tiers. Obviously it doesn't have to be this way, with a bit of business sense and some price quotes in advance. And charge extra for postage or take it into account FFS. If your $100 tier costs $80 to produce and you're unhappy with $20 towards the game from that tier, then charge $110 and you'll probably sell a similar number of packages - still more contribution from that pledge than a $20 digital tier.
But collectors have a wide range of budgets and interests, hence why most kickstarters offer a basic physical box and then more expensive ones with signed copies, figurines, dice etc. This way you get the maximum possible out of each category of collector. If you just take the approach of "cheap dvd box at an insanely high pledge" then you may sell a few to those with deep pockets, but you're not getting anything from collectors with less money or those interested in stuff like figurines, artwork or whatever. Perhaps they'll just get a cheap digital tier or won't pledge at all. Overall, less money towards the game.
tl;dr: Yes, some devs fucked up with physical tiers before, doesn't mean it always has to be this way. Just set the prices at an appropriate level (and decide if your campaign is big enough to make it worthwhile - no point in arranging all this for a handful of people).