I think buses should have rules that, unless a pushchair/pram is in fact a medical aid/wheelchair, you don't get on unless its folded.
Can't fold/won't fold - no bus for you.
That will then cause parents who need to use public transport regularly, to choose devices that are easy to fold one handed, and/or use slings.
In turn, that will increase pressure on manufacturers to make devices that fit public transport requirements.
And if you all refuse to pay stupid money for these things and only buy the cheaper ones, the prices will come down as well - so if you do need to buy two different buggies for different jobs, that's affordable.
If you think that's unfair or that if you have more than one child, you will struggle to get on public transport at all.... I honestly have very little sympathy.
As a wheelchair user, I have multiple devices, they cost thousands, between 2.5 and 13K and I funded most of that myself (bar the £450 the NHS supplied). I also still need an indoor powerchair, I'll have to find 1K for that myself with the NHS supplying the rest.
Some of these devices are NOT suitable for public transport, too big, too bulky - I don't use them on public transport, I use something else.
If I have to do this, and this is for the rest of my life, not just a few years of my life - why shouldn't other users of bulky equipment have to provide suitable equipment for the task and environment at hand?
Of course you may say there are very few wheelchair users on buses anyway - in some places that is true, not because we don't want to use them, but because getting to them, getting on them, finding space, is all such a bloody lottery and a stress, we often either don't go out, or take more expensive options!
On top of that of course, worldwide theres only a max. of 15% of people who NEED a wheelchair, who actually HAVE a wheelchair (and I would think the stats for those who have a wheelchair that actually meets their needs vs those who have something thoroughly inappropriate are even more shocking).