The most basic reason for disposable razors is because they are relatively inexpensive to buy and use and can be thrown out when they become dull or useless.
Yes, you can bring a disposable razor in your carry-on luggage.
Use a match box and sharpen on the striker.
Yes, you can bring a disposable razor on a plane in your carry-on luggage.
Yes, you can bring a disposable razor on an airplane in your carry-on luggage.
Yes, you can pack a disposable razor in your carry-on luggage.
Yes, you can put a disposable razor in your carry-on luggage.
Yes, you can bring a disposable razor in your hand luggage.
Yes, you can carry a disposable razor in your carry-on luggage.
Yes, you can pack a disposable razor in your carry-on luggage.
Yes, you can travel with a disposable razor in your carry-on luggage.
The straight razor.
Yes, you can typically take a disposable razor in your hand luggage when traveling.