Its all relative, if I may use a car analogy - its like someone who's being driving a Fiesta for 3 years. They remember when they started they used to let the car cut out, grind the gears etc. Now they drive competently, smoothly and safely, can do hill starts and parallel parking and they think "I'm a good driver". Which they are, when they're in their own car.
So then they decide it time to get a new car. Off they go to test drive a BMW explaining to the seller that they're a competent driver etc. Get into the driving seat, key in the ignition, put in gear about to set off, what happens? The car stalls. I won't go through the whole scenario but you can imagine it yourself, all gear changes are rough, can't find reverse, brake and the car stops dead, try indicating but keep hitting the wipers... EVEN THOUGH the seller said twice "indicators on the left, wipers on the right".
At the end of the test driver the seller is livid and the buyer is mortified.
Does it mean the person can't drive or over estimated their abilities? No it just means that they don't have the experience to drive every car competently. I bet if you gave them a week in the BMW they'd be fine. Unlike a mechanic who can get into any vehicle and drive it well.
I'm not for a second suggesting that you give your horse away for a week mearly trying to explain that there are riders who don't even realise that there are horses out there who could bounce them right out of the saddle with a single trot stride! Its a lack of overall experience riding different horses. Ignorance is bliss!
