I've watched a lot of Formula 1 lately, where 200mph+ crashes are a regular occurrence. More often than not, the drivers walk away without a scratch.

What is to prevent glider cockpits from implementing similar safety designs?

The primary factor that imparts superior crashworthiness to F1 and Indy cars is the suspension and wings that are sheared away during impact. As components are peeled off, energy is expended and deceleration happens over a longer period of time. By the time the "tub" surrounding the driver's cockpit is next in line for a pounding, the deceleration that has already taken place reduces the energy imparted to the remaining structure. Additionally, the design of the cockpit has multiple layers of extremely strong carbon fiber and Kevlar formed in such a way that forces are redistributed around the structure and withstand penetration and crushing. The many and regular crashes occurring over the years have provided a wealth of data for the design of each succeeding generation of racing cars. Very little data is collected for the teeny-tiny sailplane market, with only three or four manufactures worldwide.

Modern sailplanes comply with CS-22 crashworthiness standards that spell out minimum requirements for structural rigidity and cockpit penetration. Unfortunately, bringing crashworthiness up to F1 standards would require a cockpit that would be lots heavier and might not help much at all, as the deceleration of the little pink body inside is difficult to control. You can scramble an egg inside the shell.

Perhaps the next generation of composites (graphene, etc.) will allow for more robust structural integrity, but be prepared for a large price increase..