Depends on how you define 'suitable' really - suitable to their personal needs, desires or financial situation, or suitable to contribute to lower emissions etc.
As to the best way to allow more people to get to where they want to go with minimum change to current road infrastructure that again depends on where the start and end points are. Ideally some form of mass transit if it is within or between large population centres, but this tends to be expensive and limited in terms of start and end points - which puts people off as it's not true end-to-end transport. Tram systems are 'in' at the moment but are very expensive in terms of infrastructure and are usually quite restrictive in terms of flexibility of routing and therefore not demand responsive. Buses are better in terms of routings and demand but are painfully slow unless they are Bus Rapid Transit (BRT), which then has the same issues as Trams as the routes tend to be restrictive and stops limited.
Outside of large population centres it needs to be flexible, quick and responsive - so could again be bus-based Demand Responsive Transport using small minibuses - but most schemes of that type have so far proven unviable in economic terms. Cars therefore remain the default choice, sometimes with Park & Ride thrown in for the last section into larger population centres.
So - as I noted, very subjective.
Personally, for me and where I live there is a limited PT option that is painfully slow to use and has a service frequency that reduces significantly before I finish work. As an example the last time I did use it, from getting on the bus to getting off it it took nearly an hour for a journey that I can make in the car at the same time of day in about 15 to 20 minutes. That excludes the walk at each end to get to and from the stop. If it were quicker and more reliable - it often doesn't turn up or sails past the stop as it's running late (not sure why as I'm pretty near the start of the route at both ends) - then I might use it but even then the financial cost isn't that far off the cost to drive.
Add in the other issues I mentioned earlier regarding my daughter and it becomes a no-brainer to use the car - to be frank you'd be mad not to!
London is a different kettle of fish altogether and PT is more the usual choice but still used to drive me mad with how long it took to get anywhere by PT when I was down there on a regular basis.