All of those are easily subverted or controlled to prevent legitimate responsibility that benefits the people.

get the ability to vote when you own land

Say goodbye to private land ownership when either the government or banks decide you don't own anything or suddenly have no money for reasons.

and/or have children

"Anyone" can have children, often far more than they can afford or look after. This would never work as a measurement of responsibility.

Or get the ability to vote when you are tax positive

See again the point about the government and banks deciding what taxes you owe, how you pay them, and if you ever manage to approach a tax positive status while others are simply given resources for free over you.

What you absolutely shouldn't do is let young useless idiots vote IMO

when you are invested in the future.

Instead many Western countries currently have old useless idiots voting and deciding things primarily focused around their own interests/future at the cost of the younger generations who will be paying for it now and decades to come as costs continually rise.

There is no simple way to fix thing simply by drawing arbitrary lines along age, tax status, ownership, or family status. Especially since many existing problems still occur when none of those topics relate to younger groups and instead come from the older ones who keep going and making things worse for others while living in gated communities detached from reality.