...by implementing a $30/hour minimum wage?
The cost of everything would skyrocket, because it's not just the people at the bottom of the wage scale who will see the big pay bump, everyone will.
If a grocery cashier is making $15/hour and the head cashier of the same store is making $30/hour, do you think that head cashier is going to be willing to have the additional work and responsibility for the same pay as a new hire? Of course not - they're going to want a commensurate raise as well. Think a minute about what that will do to the price of groceries...most grocery stores work on tight margins, usually around 2%. So now you've got a massive increase in the cost of labor at the store.
But their wholesale prices are going to go up as well, since this same model (raise the lowest and you have to raise everyone) is being utilized all along the supply chain.
Wholesale prices go up, retail labor goes up, and there is no way to not raise prices.
And that's going to happen across the economy. Most products/services have a higher margin, so they'll most likely be able to raise prices less, but for groceries, which everyone needs, it would be hugely inflationary.
And let's not forget about public employees...should a school teacher just starting out be expected to work for only $10/hour more than some someone who is flipping burgers at McDonalds? Of course not, so teacher salaries go up, which means property taxes go up, which means rent goes up.
So yes, paying the lowest wage workers $30/hour would put more money into the economy, as they would be likely to spend the increase, but it would also result in severe inflationary pressure across the board, as well as job loss due to labor costs and increased focus on automation.