I've read over this whole thread a second time and took notes in an attempt to see if I can identify good ideas or spot places where I can provide advice. Here is what I have:
THE GOAL
Fists of all, I think that the goal here is less than clear. I'll state my goal. I want to enable corpies to do cool things like hiring mixers to do stuff that would benefit their corp. I want corpies to be able to slowly gain wealth if they are proactive and for that rate to increase if they are willing to take risks. My goal is not to make it easier to increase a corpie's personal wealth. So my focus is on spending power.
SIDE GIGS
As I and others have stated, I don't think a lot of side gigs are very themely for most corpies. I don't want corpies running crates or delivering coffee. If they do something demeaning like this it should be fore a very powerful person who can do great things for them.
Even if we did create 'automated means of income' for copries, they would be useless. Most corpies already make more than the weekly cap with their salary alone. I guess we could consider upping the cap just for corpies but I'd rather not. That cap is there to encourage PCs to engage other characters and RP and not just do automated jobs all day.
GM OVERSIGHT AND EFFORT
I honestly don't think that approving reimbursement requests requires all that much time and effort on the GM side. The systems we have are clean and easy for us to use. Also, I think you all underestimate how much oversight we put into mix side hustles. It takes a different form and is less visible to players but it is there.
THINGS FOR JOB X TO DO
We can certainly improve here and we want to. There is, however, a lot players can do on their own too. Are you a bio-tech? Convince someone you need test subjects. Are you a requisitions guy? Get insulted at the mixer who stood too close to you in the Lev and lie to your CorpSec people about how you overheard them talking on the phone about bombing your corp. Chemist? Play with the various strains and convince people you need guinie pigs (willing or not) to test your drugs on.
We want to improve things here but don't wait on us. Go make your own stories.
REGULAR ASSIGNMENTS
This idea proposed by Grizzly and Talon is a lot like what I laid out. The difference is that I want to see players create their own assignments and do them. Don't wait for GMs to hand them out. Honestly, half the time we do hand them out the PCs just drop the ball or ignore it anyways. I've tried. A lot.
Doing this cover's two things: Buying Power and Personal wealth. You get buying power when you know what kind of things you can throw flash at and be confident the corp will reimburse you for it. You should be trying to learn this so that by the time you are out of Junior you can start doing cool things. The personal wealth comes from rewards of being proactive and driving RP and increase by being shady here.
BUDGET AMOUNTS
This is an IC thing. If you feel the budget is too limited then tell your boss. Be ready to justify a change. These aren't set in stone. But I rarely see budget being a real issue. And remember that people are more likely to get flash to do cool things with then they are if all they want to do is to buy themselves the next new shiny thing.
GENERAL ADVICE
1. Get hired at a good time, when you can handle the step up.
2. As a Junior, put in an effort to learn what you can safely spend on in the corp's name
3. Out of Junior, start spending and driving RP. Even if every corpie did just one cool thing a month topside would explode with activity.
4. Remember that IC rules can be broken. Should be broken even. No risk, no reward.
5. Remember that you can be a mix loving whore as long as it's done discretely or framed right.
6. Cash flow matters more than account balance. Yes, you need a decent chunk of flash to front expenditures. But once you have a decent amount, the flow will be beautiful if you can tap into corporate flash - even if you balance doesn't raise crazy fast.
7. Every so often stop and think about what your PC could do to stir things up in a way that your corp will like and pay for. Is there a problem that needs solved? Can I create a problem that needs solved?