The nfl testing regime is purely surprise testing based.
The bigger difference is that endurance sports have more options for doping than others.
Frankly, I think too many things are banned. Blood doping seems no worse than sleep chambers and hgh in correctly applied regimes would take some of the punishment out of football.
Maybe read some of the stories of the cyclists like Pantani doing blood doping. They would have to wake up every few hours through the night and do some cycling on a stationary bike to get their heart rate up or their heart might stop while they're asleep due to their blood being too thick. Sleeping in a hyperbaric chamber to boost the mitochondria is childs play in comparison.
The NFL (and other major sports organizations) have no incentive to catch their athletes beyond a token amount to make the general public think the league cares about it. They don't want to catch too many as that could lead to a PED scandal that damages the reputation of the league; for example the BALCO scandal in the early 2000's MLB. Plus PEDs allow their athletes to stay healthy and perform at higher levels.
There's a reason athletes refer to PED tests as IQ tests. Only the very dumb or careless get caught, but the reality is nearly all of the athletes in these leagues have used PEDs at some point in their career.