If you’re in a wheelchair, staff will assist you with a ramp when boarding, and they will arrange for someone to be waiting with a ramp at your destination stat

If you’re in a wheelchair, staff will assist you with a ramp when boarding, and they will arrange for someone to be waiting with a ramp at your destination station. And you can take a bike, it’s just has to be in a bag. Inside the bag, you’re supposed to have the front wheel and pedals removed (in practice people don’t remove pedals), and the handlebars turned 90 degrees. It works fine so what you’re really arguing is for tolerating delays, reducing capacity and inconveniencing everyone else just to make it extra convenient to bring a bike on board. It’s like arguing that you should be able to bring your bike on as a carry-on in a flight.