I have thought about it and I agree. Young people do not demonstrate the maturity and responsibility necessary to be considered adults at the age of 18. So I have a common sense proposal.
Twenty-one will become the standard. All the Constitutional privileges of citizenship should come with some responsibilities. Activities that have become commonplace for minors need to be reexamined.
Free speech is too dangerous to be misused by children, so we will restrict use of the internet and other public forums to adults. 21.
Voting is too powerful a activity to be misused by children, best if that responsibility is something only adults participate in. 21.
Drinking is already 21.
Driving? Clearly the insurance data shows how dangerous it is to give a 16 year old a vehicle and permission to operate it on public streets. Driving should be 21.
Cell phones have their use. Children's cell phones should connect them to Mommy and Daddy and 9-1-1. A smartphone? You could get your adult smartphone at 21.
Higher education should not be attempted until you are an adult. High School could be extended one year, or schooling started one year later to allow for the overall immaturity of the children. After High School, everyone would 2 years of service. Military, Peace Corps, Vista, CCC, some kind of paid, supervised work that allow them to participate in
Signing for a loan? Signing a student loan? 21.Letting an 18 year old encumber themselves with tens of thousands of dollars in student loan debt is just abusive. Even the students think so.
Let's give it a try. If it doesn't work out, we could raise it further. Right now, children can stay on their parent's health insurance until they are 26. Maybe that is when adulthood begins.
If you have some other ideas on what activities should be restricted to adults, put them in the comments. I'm starting a movement.
It's for the children.
Updates: From the comments
From Odysseus: Age for military conscription. 21.
From B: Age of consent for sexual activity and marriage. 21. (Might really need to be 25 to reduce the divorce rate, click for the statistics.)
From Allen L.: Age for ownership of land. 21.
Age to sign for building permits. 21.
Age to receive any inheritance held in trust. 21.
Age for independent banking. 21.
Age to sign for business licenses and any form of bonding or insurance. 21.
Age for being eligible for any licenses for conveyances on land, sea, or air. 21.
Age for rentals of any sort of equipment. 21.
From SiGreybeard: Age for owning a device capable of texting. 21.
(As SiGreybeard points out, The National Safety Council reports that cell phone use while driving leads to 1.6 million crashes each year. Nearly 330,000 injuries occur each year from accidents caused by texting while driving. 1 out of every 4 car accidents in the United States is caused by texting and driving. 78% of all distracted drivers are distracted because they have been texting while driving.)