One of the biggest problems we have in the ebike world is the actual cost of the motor and battery seriously pushing up the overall price, so the basic minimum is the 1000/1200 mark.
But for that huge outlay what you are actually getting is what have been termed as a BSO, this stands for bicycle shaped object, to which the company have fitted a battery and a motorized rear(or sometimes front) wheel.
The rest of the bike, the important parts than give it longevity and make riding a pleasure are as basic and cheap as it is possible to get.
Components on these 'BSO' are from makes you've likely never heard of, chosen because they are extremely cheap, likely not up to the task set of them, because the company needs to make a profit, and the cheaper it costs them to make their 'Ebike', the more profit that get to keep.
Many use the name 'Shimano' to describe their gearing system(Derailleurs, gear changers) but theres a wide range of shimano gears starting at under 20 quid and going up to hundreds of pounds for each component part. Each of those is set at different levels of use, and at under 20 quid, the manufacturers Shimano arent expecting the bike to be putting in any considerable use, but more like the basic occasional usage.
The same criteria is applied to the most important part, which is the braking system. These Ebikes are heavy, and even the basic is heavier than an analogue downhill bike built for brutal descents, so to effectively stop the bike, especially in an emergency, you need the brakes to work and work consistently, with the minimum of user interaction. Like your car brakes, they need to work day in and day out and do the job they are supposed to be doing. But manufacturers just coin 'Disc brakes fitted' without expanding on what exactly those disc brakes are and there are two types, cable, which lack power, which is something not really designed for a 20kg bike or hydraulic, which are better but again there are hydraulics and there are hydraulics and the price range runs from £40 for a bikes worth to £400, and like the gearing above the cheaper usually opt for the cheapest option in that range.
This same criteria and placing the most basic of components, which in my mind is totally unfit for purpose is what is wrong with the Ebike market today.
At 73 i wouldnt expect you to be taking on any brutal downhill descents, but at the same time i would expect you to understand the need for componentry that is built to last and built to do the job it is supposed to do.
I see bikes priced at a thousand pounds, i know instinctively what level of component on a non ebike that amount of outlay would give you, but on the majority of these BSO's i see manufacturers names on components ive never heard of and usually have to google to find out what they are.
Even at £1200 as a basic minimum, the actual 'bike' you are paying that extraordinary sum for is in the realms of a £200-£250 catalog or mail order bike the type you see for sale in Argos or even Tesco.
I think you should look towards conversion kits and a better quality 2nd hand donor bike to fit it onto.
Or continue to save towards a better branded bike, at least until stocks are more available, which could be another year.