I would like to know if there is a way to make it so when a player places a block of TNT, it immediately fuses, without the use of flint and steel, fire charges, etc.
Please, no mods or plugins.
If you want to use a command block to remotely prime it, just use
/setblock <coordinates> minecraft:redstone_torch to place a redstone torch next to the TNT (you can replace
minecraft:redstone_torch with anything that would output a signal like).