I agree about kamikaze mobility scooter drivers / riders, especially inside shopping malls and shops. Mind you were in Morecambe last week having a stroll along the fairly wide promenade and the number and speed of bikes along there sharing it with pedestrians but whizzing up behind you and through gaps between pedestrians was alarming, and no bell to warn you, as usual the full lycra wearing tour de France wannabes were the worst offenders..
Cyclists on pavements.
Don't get me started 
To be fair, the cyclists are actually committing an offence by cycling on pavements/pedestrian areas, but mobility scooters seem to be a grey area - they certainly seem to think they have every right on pavements, and on roads for that matter. I just think they should be restricted to pedestrian speeds.
In Morecambe, the cycle lane is on the Promenade, so not illegal, but stupid design. It is about time we:
- created properly designated cycle lanes that can't be blocked by parked cars and clearly separate cyclists from pedestrians and cars.
- made parking across a pavement or cycle lane illegal
Where I live, the Cycle Route 66 passes through the Pennines by using a variety of means, one of the most common being the canal towpaths. As a runner, cyclists approaching me from behind are a real menace. Once I was leading a small group of runners and a bike came up behind, silently. I never run with headphones in, so I heard him and shouted 'BIKE' to warn my colleagues.
He said 'sorry, I fell a while back and my bell broke'.
I said 'did your voice break too?'
On the canal towpath the priority is pedestrians first (which includes runners), then bikes. But cyclists seem to forget that. Cyclists must give way to pedestrians. However, pedestrians need to be realistic and not unreasonably block the cyclists.
