Firstly, don't trust the Glassdoor reviews as staff are prompted to add a review after 1 month of being there. Obviously it is too hard to make a informed comment after 1 month.
Secondly, the pay is just not competitive which encourages good staff to leave. Turnover in my team is around 50% p.a. Finally, the benefits insurances, gym pass, ebike subscription, L&D budget probably aren't worth how long they cost everyone to administer. Just pay people an extra allowance each month and let staff decide how they want to spend their money. Feels a bit socialistic.