I'm not sure what you're responding to. I asked you to compare Texas law of illegal possession (which you posted which is really light, I agree) to California and Illinois.
California:
"Unlawful firearm possession can result in up to $10,000 in fines and up to 3 years in jail – and you could lose your right to possess a firearm in California for the rest of your life. For all these reasons, you need a good defense."
So if properly enforced, you could put someone away for 3 years if you chose to. DAs don't choose to. Thus, the weakness is in the enforcement.
Illinois:
"A class A misdemeanor is punishable by up to one year of jail time and a fine of up to $2500. If you fall into one of the above categories that exclude eligibility for a FOID card, you will be charged with a Class 3 felony. A class 3 felony is punishable by a five-year prison sentence and a fine of up to $25,000."
Since almost all criminals would fall into the exclusion of a FOID card category, that means they'd be subject to a 5 year sentence - which coincidentally is what you said would deter criminals if it were implemented. That doesn't seem to be deterring criminals in Illinois (Chicago), so either they know its not going to be enforced (my argument) or they aren't deterred by it. Or both.