Consider the "pay it forward" notion here. You were once a child, given life (intentionally or not, it wasn't your will), and with that all the benefits you enjoy...the sheer ability to appreciate a fine leased luxury car...your senses and conciousness has been given to you. As has all the food to have sustained you over the years, as has the shelter, protection, love, encouragement, education and so on.
Your very existence up to the age of say 15 is entirely a debt you owe to someone, some institution (government health care, social services, education, etc). Without any of that you wouln't have the basis to appreciate a single wonderful good thing / toy in this world. Your parents bought you toys, yet now you cannot share...interesting.
The debt you owe your parents alone can never be repaid. You will never spend on them, or wipe their *** as much as they have done for you.
The notion is the debt is paid forward, and experiences afforded to new souls / minds / what have you. Hopefully these experiences are worthy of transmission.
Your civic duty is to at least have 2 children to maintain population and culture. If this is not done, you will have an immigrant demographic shift, as (specifically) this country exploits immigrant labour to keep the naturalized population working in the service sector and at a higher living scale.
Once immigrant influx / births exceeds domestic growth rates you will have a cultural shift. You wont care because your lease will be over and you will be in an old age home having your RRSP or savings bled dry by an inflated cost of living index. Or you may even opt for an early death when life without your toys becomes unbearable. You wont have anyone repaying the reciprical debt of love and gratitude to you in your old age, because....no one wants to share their toys. There will be no children of yours to share their dinners, grand children, homes, cars, picnics, death beds with.
Long term and indirect reciprocity is the issue here. Taxes is an indirect long term reciprical notion as well...pay into the pool (pay it forward) because one day you may need to call on a huge favour. Hell even the private sector espouses it (with a proffit mark-up of course): insurance. That leased luxury vehicle has mandatory insurance requirements....even if you never get into an accident, you have to pay into the social welfare pool, otherwise the whole system breaks down. So taxes are madatory, insurance is mandatory, licencing is mandatory (to grant you the provelege to drive)....there is a whole system in place, that existed prior to you, that you simply play your required part in, to be able to enjoy certain aspects of life.
Having children is a biological and societal tax...it is just not mandatory. I am not saying have 10 children divide up the "American (dream) pie" so much so that no one gets a good sized chunk, but if you don't have 2 children, that pie will be gobbled up by another (passively) invading culture (if you're lucky). But as I say, you'll be long gone...
Come to think of it, why do you even pay tax or insurance? How can they force you to do that? Shouldn't one be free to not pay? Ah yes you can opt out, but then again you opt out of civilization also, and you opt out of the rewards and benefits of the system.