But in this scenario, the amount of money doesn't change. It's just a matter of defining what percentage of the total salary cost of employee is attributed to the employer vs employee.
For example in Estonia, if you hired somebody for 1000 EUR gross salary (the number that you'd put in a job listing), the employee would receive 896 EUR on their bank account and the state would receive 442 EUR as taxes from the company. This means the cost of this employee's salary is 1338 EUR (1000 EUR gross * 33% social and 0.8% unemployment tax) to the company. This is not optional, the company can't decide to pay less or use the money for other purposes. This would show up as 1000 EUR in statistics for average salaries or comparisons like this.
You could shift this tax burden between employer / employee arbitrarily and say for example that starting next month, social tax will be counted as part of gross. However the employee would still receive 896 EUR to their bank account and the state would still get 442 EUR as taxes and the company would still pay a total of 1338 EUR, but the average gross salary just went up by a third, while nothing actually changed.