Does the third "ground" prong on many American electrical plugs improve safety? If so, why are toasters and similar appliances often without a ground prong, when low-voltage devices (like Apple laptop cords) often do have them?
https://www.quora.com/Does-the-third-ground-prong-on-many-Am...

The NEMA 5-15 plug has two flat parallel blades like NEMA 1-15, but also adds a ground (earth) pin.[84] It is rated 15 A at 125 volts. The ground (earth) pin is longer than the line and neutral blades, so the device is grounded before the power is connected. Both current-carrying blades on grounding plugs are normally narrow, since the ground (earth) pin enforces polarity. NEMA 1-15 plugs are also compatible with NEMA 5-15 sockets.
https://en.wikipedia.org/wiki/AC_power_plugs_and_sockets#Nor...

All NEMA 5 devices are three-wire grounding devices (hot-neutral-ground) rated for 125 V maximum, with the 5-15, 5-20 and 5-30 being grounded versions of the 1-15, 1-20 and 1-30, respectively. The addition is a 3⁄16-inch (4.763 mm) diameter round or U-shaped ground pin, 1⁄8 in (3.175 mm) longer than the power blades (so the device is grounded before the power is connected) and located from them by 1⁄4 in (6.35 mm) edge-to-edge or 15⁄32 in (11.91 mm) center-to-center.
https://en.wikipedia.org/wiki/NEMA_connector#NEMA_5

A cheater plug, AC ground lifter or three-prong/two-prong adapter is an adapter that allows a NEMA 5-15P grounding-type plug (three prongs) to connect to a NEMA 1-15R non-grounding receptacle (two slots).[1] They are needed to allow appliances with 3-wire power cords to plug into legacy ungrounded (two slot) receptacles found in older buildings. The use of such an adapter avoids the need to replace receptacles, but is potentially hazardous if the grounding tab is not connected to electrical ground.
https://en.wikipedia.org/wiki/Cheater_plug

Note: You should replace "ground" by "earthing" if the target language is EN(UK) rather than EN(US).