It’s both surprising, and not, if you think about it. The way I’ve usually seen it happen is first the rear tire goes flat, then the front one. My theory is that both tires went through the same pile of glass/thorns/metal bits and they both picked up junk. the reason for the flat occurring on the back first is because there’s more weight on that tire, so the offending article works its way through the tread more quickly.
A bicycle costs anywhere from $250-$9,000 depending what type and quality of bike you want. A utility bike from a department store might cost $300-$500, but experts caution that it will be quite a bit heavier and not as well constructed as other bikes. For a durable, lightweight bike with front-suspension and decent parts, it’s reasonable to pay $750-$1,200. You might be able to pay slightly less, but expect to need some repairs after several months of heavy use.
Brakes come in a variety of designs depending on the age and style of your bike. Rim brakes offer more modulation but have less stopping power, so are more suited to riding on the roads. Disc brakes can provide huge amounts of stopping power so are best suited to off road riding, although ‘V’ rim brakes are also well suited to mountain biking. All brakes use a friction system to stop the movement of the wheel, so regular checks of the contact pads should form part of your regular cycle maintenance.