Turnover is extremely high because of the highly stressful and incredibly soul-crushing nature of the work. In fact, every year, a 4 month hiring process begins in the summer to recruit and hire a fresh class of first-year associates. Yes, the organization is slightly expanding and therefore can offer more opportunities, and yes, there are so many recent law school graduates that the candidate pool is truly massive. However, the reason the organization spends ⅓ of the entire year searching for the next batch of lawyers to work for them is because a near-equal number of current associates are guaranteed to resign. Totaling hiring and recruiting efforts for all positions, lawyer or others, and the organization is literally advertising, interviewing for, and filling at least a dozen openings on average at all times, regardless of season. The Hiring Director fully understands that the organization is incapable of retaining employees for any meaningful period of time and treats high turnover as a given.
Management is largely absent or isolated from the average staff member; locating and/or connecting with department heads can be a massive chore (most departmental heads are also practicing lawyers and spend most of their time on the move). This can be even more frustrating when you consider that different the different practices are housed in completely separate buildings altogether, with all non-practice departments (community relations, administration, operations, technology, human resources, etc.) mashed in wherever there is room. Floor plans and directory maps are available--good luck making heads or tails of any of them.
Line between junior and managerial/directorial staff is thick, clearly drawn, and largely impermeable. The vast majority of sub-managerial staff members, whether associates or support staff, have virtually no path or potential for upward mobility within the organization, and are aware of such (hence the high turnover rate). Higher ups seem too far removed and, frankly, unconcerned with the issues their sizable junior staff are actually dealing with. Many of the managerial/director-level staff are not promoted from within, but headhunted and hired from outside the organization, so they cannot sympathize with their own subordinates. The culture is not conducive to mixing and networking between senior and junior staff, so rarely, if ever, shall the twain meet. This, too, factors into the absurdly high turnover rate.
The office politics amongst the higher-ups is significant, and disagreements or miscommunications are often blown out of proportion or completely blamed on subordinate staff members who have no recourse to defend themselves or protect their standing in the organization