Because the gov't probably never funded any studies into this.
QUOTE
For marijuana, and for a number of other legal and illegal drugs including antidepressants, painkillers, stimulants and the like, there is no statistically significant change in the risk of a crash associated with using that drug prior to driving.
...
Several states have passed laws attempting to define "marijuana-impaired driving" similarly to drunk driving. Colorado, for instance, sets a blood THC threshold of 0.5 nanograms per millilitre. But that number tells us next to nothing about whether a person is impaired or fit to drive. The implication is that these states are locking up people who are perfectly sober.
Wait, you mean the various legal agents in this country are criminalizing citizens who aren't actually the danger they're purported to be? The hell you say.
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Diogenes of Sinope:
"It is not that I am mad, it is only that my head is different from yours."
"Other dogs bite only their enemies, whereas I bite also my friends in order to save them."
Arnold Judas Rimmer, BSC, SSC:
"Better dead than smeg."
