It only seems that way because those are the ones you know about.
3 years mandatory for 1 plant.
[TABLE="width: 652"]
[TR="class: sectionTitle, bgcolor: #C5E5BD"]
[TD="colspan: 4, align: left"]Cultivation
[/TD]
[/TR]
[TR]
[TD]1 oz - 5 lbs (less than 10 plants)[/TD]
[TD="width: 20%, align: left"]felony[/TD]
[TD="width: 15%, align: left"]3* - 5 years[/TD]
[TD="class: amount, width: 20%, align: right"]$ 25,000[/TD]
[/TR]
[TR]
[TD="width: 40%, align: left"]5 - 25 lbs (10 - 49 plants)[/TD]
[TD="width: 20%, align: left"]felony[/TD]
[TD="width: 15%, align: left"]5* - 10 years[/TD]
[TD="class: amount, width: 20%, align: right"]$ 150,000[/TD]
[/TR]
[TR]
[TD="width: 40%, align: left"]More than 25 lbs (50 plants or more)[/TD]
[TD="width: 20%, align: left"]felony[/TD]
[TD="width: 15%, align: left"]10* - 20 years[/TD]
[TD="class: amount, width: 20%, align: right"]$ 300,000[/TD]
[/TR]
[TR]
[TD="colspan: 4, align: left"]* Mandatory minimum sentence[/TD]
[/TR]
[/TABLE]
MANDATORY MINIMUM SENTENCE
When someone is convicted of an offense punishable by a mandatory minimum sentence, the judge must sentence the defendant to the mandatory minimum sentence or to a higher sentence. The judge has no power to sentence the defendant to less time than the mandatory minimum. A prisoner serving an MMS for a federal offense and for most state offenses will not be eligible for parole. Even peaceful marijuana smokers sentenced to "life MMS" must serve a life sentence with no chance of parole.