Whilst I agree with the sentiment of not lifting if you don't feel it's safe or you're not physically able, the idea that you cant/mustn't lift anyone from the floor is nonsense.
Firstly - theres absolutely no legal risk in rendering first aid measures in the UK, helping someone up is absolutely first aid and no one is coming after you - you're extremely well protected. It would only be a risk in something as mad as "please don't move me I can't feel my legs", "don't worry I know best I'm going to pull you up into this chair, stop screaming, you'll be fine when I get you up...".
Secondly, and I say this as someone who works in the ambulance service frontline and on the phones - we probably aren't going to come until they've been on the floor so long they start deteriorating and becoming unwell. Unless you live in an area with falls teams (often volunteers), or its particularly quiet.
That's why you occasionally hear about 90yr old Dorris who slipped on the driveway in January and couldn't get up, left on the floor by ambulance service for 8 hours.... It got to the situation where there are so many frail people living on their own falling multiple times a day we just don't have the capacity to cover it, if there's no injury then not classed as an emergency and goto the bottom of the list. If it's busy then who ever called will get the no send script, if the person is on their own then we call neighbours etc to see if they can help. If it's a care home following a 'no lift' policy we have to make them aware that as they have lifting equipment in the home, they have the means and a duty of care to look after their residents, that because there is no injury apparent we can't come until it becomes an emergency (long lie/over an hour on the floor can cause kidney failure -our response time is commonly 4-6hrs), can I take your name because I need it documented who's refusing to get them up which is likely to lead to patient harm...I advise you to make sure you've got a copy of the no lifting policy and be sure that your employer really has taken on this duty of care for themselves."
What makes it worse though is that we are all blue lighting around to 30yr old with 4month history of back pain (some triage tool thinking it's a heart problem), 4yr old with fever (very mobile, just needs running upto a&e in the car and if it does turn out to be meningitis then you'll be seen at least an hour sooner by making own way). Just doing my drugs audit for the year last month - I'd only had to administer medications to patients 23 times in the last 12 months - of all the patients I'd been sent to only 23 needed treatment beyond a chat and a ride.... Oh and a good chunk of that 23 was oral paracetamol.
We absolutely should be prioritising elderly fallers over the nonsense we spend our careers going to. But you've got to remember that in a city of 500 000, you will have around 30 ambulances on duty in the day, 20 at night. If we are the only ones picking up elderly fallers we are not going to be doing anything else.