It would have helped MY peace of mind to know that Asking my first question, + waiting 20 minutes would be enough to get me the rep so that I can start Upvoting questions and answers!
If you have an account with +200 reputation anywhere in the Stack Exchange network, you will start on all new sites with +100 rep for a total of 101.
Beyond that, we encourage the truly new users to contribute a bit and give the community the opportunity to get to know them and vote on their posts .. before we give them voting permissions.
As for meta, it's tricky. I would like to allow new users to participate here but it's almost impossible to do so without risk, because metas are very low traffic and a malicious new user could cause a lot of damage by posting junk. Thus the 5 rep requirement to keep the bar as low as possible -- at toe level at least.
There is also the argument that participating on meta is a (very minor) privilege that you should earn by at least participating on the main site for a little while, so you have a basic level of familiarity with our sites and how they work. We get a significant number of brand new users who come into meta.so (which allows 1 rep participation) and start explaining how we're all doing it wrong, our entire system is broken, the sky is falling, etc etc. All the old timers just roll their eyes..
Want to get the ability to upvote? Ask a question. then wait 20 minutes. Then you'll be a "full member" !