What do you mean by "hiker/biker"?
If you mean designated campsites in parks or campgrounds where the cost is about $5 per person -
Then, no - there aren't many, unfortunately.
Oregon is, by far, the best.
California's used to be pretty good, but Calif has been slammed by budget cuts.
Washington State Parks have some mowed area off to the side without even a picnic table.
Many National Parks - esp. in the West - do have nice hiker/biker sites.
Longer distance rail trails often do have a few hiker/biker sites - such as the C&O or the Katy -
But they do tend to be on the primitive side.
If you are talking about cheap/free camping - -
You can camp for free on most federal National Forest Service and BLM lands.
Or course, you need to know where they are and the boundaries.
Most state forests also allow you to camp free or cheap -
Most federal and state wildlife areas do not permit camping with some exceptions.
Many Montana Fishing Access Sites (FAS) do permit free or cheap camping.
Often just a portalet next to a small parking area - but always on the water, of course.
These are often lovely, out-of-the-way places to camp.
Ditto on small towns in the Great Plains - the smaller, the better.
If there's a KOA by the interstate, they are not likely to let you camp in the town park.
Because the west coast has hiker/biker camping - the east coast tends to be worst.
But did you know that you could camp way out Down East in Maine on bluffs overlooking the ocean?
Cutler Coast - -
State Parks and Public Lands: Maine ACF - Search Results
Or under Verrazano Bridge on Staten Island?
Or on the beach at Cape Lookout?
Takes some digging - but stuff is out there.