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First need to see a simple circuit.
Voltage is a difference between two points, and in this case for R2 difference is zero, so no current into. Later no matter what resistors we add, the situation doesn’t change.
This is mainly the effect that we are dealing with an ideal voltage source, so the internal resistance of an ideal voltage source is zero. In theory no matter if we have placed also a resistor in parallel for V1, the voltage will remain the same. In practice no real voltage source is ideal; all have a non-zero effective internal resistance, and none can supply unlimited current. See the example attached.
If KVL is applied, the equations seems to be quoted incorrectly. There can't be contribution of I1 and I2 in both the equations. Just keep the currents I1 and I2 specific to loops independently. They will come out to be 2Amps and 1Amps respectively.
Try the Ohm's law.
It states that the voltage drop, V, across any resistive element is proportional to the current , I, flowing through it.
Further, the constant of proportionality is the resistance, R, of the element.
In our example across the resistor R2, the voltage drop = 0 so the current is 0.