Why?
Waaaaaaaay back, d'you think the budgets were any closer? F1 has lasted a long time with that state of affairs. Christ, I hate what the difference front-to-back was in '54 and '55 when Mercedes went on their rampage. I'm pretty sure Lotus never had particularly vast amounts of cash. Cooper certainly didn't. Throughout the World Championship era, there has been a distinct gap in the funding between teams. But that's alright, it still allowed for stuff like the Jordan 1991 campaign - a well-run team with a simple but effective car beating up on teams with much higher budgets.
F1 owes no-one a living. If you can't afford it, get the hell out. Still, I do feel sorry when stuff happens like the demise of Super Aguri - they only folded because of a sponsor not paying money promised to them. They certainly had the potential to 'do a Minardi' and hang on in there for a long time, picking up the odd heartwarming good result.