The rate of single parenthood (particularly low income single parenthood) has been exploding in the West, concurrent with rising social welfare spending.
As for the general birthrate, that seems to be affected by income, not the availability of welfare. This is indicated by examples like Hong Kong and Singapore, which have much lower levels of welfare than most developed countries, and much lower birthrates.
The government can charge rent for utilisation of land and other natural resources. That's not the same thing as a tax, and it can be morally justified.
Revenue from such rent would be enough to cover the government dealing with externalities, whether that be generating positive externalities or reducing negative ones.
Welfare is a nonvoluntary transfer of income, to force one party to provide for the basic needs of another. It can't happen in a free society. It leads to an explosion in single parenthood. When a guaranteed income is conditioned only on a person existing, then you will encourage people to bring people into existence at the lowest possible cost to themselves. That's indeed what the statistics show for Western countries over the last 40 years.
Uber is most certainly not fucked, and if it isn't Uber, it'll be another ride sharing company. Airbnb is growing rapidly and helping to create a more mobile world, where you can affordably travel, or live in different places a few months at a time.
And tourists on a per capita basis contribute far more per day than long-term residents, since they're in high spending mode. They also consume fewer government services like welfare and medical care, so they don't cost the taxpayer as much.
Airbnb also makes it much easier to rent out spare units that would otherwise sit empty. It makes it easier to rent out that extra bedroom, or your unit while you go on vacation for two weeks. That increases total housing supply. Short term housing is still part of housing supply. People need affordable options when they're transitioning from one long term unit to another. It's not always a same day transition.
Markets in general benefit mankind, by allowing more efficient exchange. This is Econ 101 stuff, for which there is mountain of real world evidence.
>Vote for politicians who are going to create real structural change in society, e.g. Bernie, not just systems maintainers like Hillary, or rich guys who want to rip us off, like the guy who won. (And really work at a local level to enact structural systems changes!)
As for the general birthrate, that seems to be affected by income, not the availability of welfare. This is indicated by examples like Hong Kong and Singapore, which have much lower levels of welfare than most developed countries, and much lower birthrates.