In time a lot of those jobs could be automated. So why not give the people who you would have do them more skills, give them a chance to better themselves? Or would you rather keep them at that level to help others feel better about themselves? You see I firmly believe that our best way forward is to automate the mundane as much as possible, and empower & enrich everyone.
I'd love that to be the case, but there are, genuinely, people who do not have the brain capacity or dexterity to do a mentally challenging or skilled job (however good the training), and if you automate out all of those jobs that gives them nothing to do. OK, you could introduce UBI and so just pay them to do nowt, but that isn't exactly great for building self-worth.
I'd agree that people who *do* have that ability need to be encouraged to move up from those jobs (though they are a good starting point - perhaps a groundskeeper could move to a manager role in the Council?) but it will not be everyone.
A wider range of jobs, all respected, means a wider range of employed people.
FWIW it'll be a long time before we can automate weeding e.g. between paving flags. We might be able to automate spraying toxic glyphosphates, but we should perhaps be looking to move away from that[1]. And CCTV is just no substitute for a bog attendant or an attentive park keeper. CCTV is good for catching people afterwards (ish), but crime prevention really requires a person there to go "oi, no!".
[1] Some Councils already have - Lancaster, for instance, as a result of which most of the residential areas, which are classic stone flags and even some cobbles, look like 28 Days Later has happened rather than a pandemic of a mostly relatively minor coronavirus.