Here's a super depressing mathematical proof of why the services fail in the burbs:

First the assumption is a car is necessary for living in general. I am very happy for the 0.1% of the population who live in an urban hugbox where they don't need a car, but this is a general argument for 99% of the population or a unicorn sized middleman app.

My garage costs perhaps $50K lifetime, including land, maint, all added together. An online mortgage calculator spat out $290/mo for my garage. I suppose as a fraction of the cost of the house its not ridiculous. Or at 20 working days per month, simply having the possibility to drive my own car costs $20 to park it at home. Use it or not, I'm out $20 per day.

I bought the cheapest toyota out there for my commute. Many people will insist on the largest SUV they can afford, but whatever. Many people will replace their car every two years to show off conspicuous consumption whereas I drive my cars into the ground because I'm super arrogant and rebellious about not impressing other people. Anyway simple straight line capex depreciation of $20K vs 250 commutes per year vs maybe a decade life of the car means each working day the car drops in value $8 no matter if I drive it to work or not.

Being a commuter car instead of a SUV I am kinda cheating on gas expense when I actually drive to work. Figure 40 miles round trip at 80 MPH (I don't live in CA LOL, and flex time a lot) and 40 / 30 mpg = 1.3 gallons burned per commute and we'll pessimistically call the average price of gas over a decade $3 (LOL) so it costs me $4 to actually drive instead of car pool.

Now there are two ways the math argument kills suburban car pooling. The first is I'm out $28/day to commute no matter if I actually commute, car pool, or call in sick. The variable cost is a menial minimal $4 to actually do it. So I do NOT save 100% of the cost of my commute, I only save about 10% of my commute cost by not commuting. Why bother? If I wanted to save 10% I'd be infinitely more likely to get an even smaller car or live in a cheaper area than to give up the convenience of my car for a mere 10% savings. This argument is like people who pay $4000 mortgage and then shiver in the dark because they can't afford the heating bill, its not that turning down the thermostat is a great idea, but its that they obviously demonstrate incredibly bad economic management to end up in a scenario like that.

The other killer is car pooling takes a lot of time, and regardless of how high or low an employer values his feudal servant's time, outside work people seem pretty happy to drop $20+/hr to get drunk or watch theater movies or whatever. So I feel $20/hr is a reasonable valuation of time for the general public. Now lets say car pooling costs 15 minutes extra wasted time at each of four endpoints, for a total of an hour. If you insist on matching up strangers online, they probably don't live or work nearby each other. Now an hour of free time is worth $20, and car pooling will cost me an hour, but save me $4... So car pooling puts me $16 in the lifestyle hole.

So mathematically I don't save much money by occasionally car pooling, and the standard of living is dramatically lower.

I tried to calculate a math model for reliability and dropped it... its hard to compare a nearly 100% reliable toyota vs a very hypothetical service that may or may not match you up after hours and may or may not match you up with weirdo axe murderers or maybe not. Basically you have one system that although expensive is nearly perfectly reliable and nearly perfectly safe, vs a pile of question marks that might ... might ... turn out as good. Maybe. But you can't build a math model off that so I gave up.