Here in the UK almost all the halls have identical 3 legged rostrums / podiums. (They are very much better looking than that hideous thing in the picture though...) Reason being is they are all made by the same business run (you guessed it) by brothers who obviously have the contract (or just know some high placed witlesses) to supply them.
If a lot of your US podiums are all similar then I'd guess it's the same deal. They will be being made and supplied by a US business run by witlesses.
The same goes for the sound systems in the UK, all are made and supplied by a firm run by witlesses. All are EXTREMELY over priced as well. Two more things I dont like, witlesses making money out of their religion and a monopoly position on the contract.