"I dispute that it is down to the fact they would make a make a loss if they ran the higher RTP versions". This is true in some jurisdictions and false in others. Germany has a 5.x% something turnover tax, which means that unless that RTP is set below 95%, the casino cannot make a profit. Other jurisdictions where the tax is based on revenue, a lower RTP is not required to make a profit but most operators are doing this regardless.